Symbols that look alike or are frequently mixed up, shown side by side with what actually differs between them.
Showing all 101 comparisons, grouped by subject.
Both are drawn as one continuous decorative stroke with a closed loop and a tail that crosses back over itself, which is why a description of the shape alone reaches both. The clef is far taller, spans a stave, and its spiral encircles one specific line — that encircled line is the note G, and it is the only reason the shape is drawn where it is.
As punctuation the asterisk points at a footnote or marks a required field. In a filename pattern typed at a shell it matches any run of characters, including none — and the shell expands it against real filenames before the command runs, so the command never sees the pattern at all. That expansion is the part people are surprised by.
Look at whether the adult is standing or seated. Baby changing shows an adult leaning over an infant on a table — a facility for changing a nappy. A nursing room shows a seated figure holding an infant — a private space for feeding. They are separate rooms, and signage that conflates them sends people to the wrong one.
In principle the ribbon saves to a reading list and the star marks a favourite or contributes to a rating. In practice services use them interchangeably, so the same action carries a ribbon on one site and a star on the next. Users hesitate over which to press because there genuinely is no rule.
The contactless indicator is four nested arcs and marks a payment card or terminal. The N-Mark is a wave-like capital N, is a trademark of the NFC Forum, and marks where to tap a device for near-field communication generally. The underlying radio technology overlaps, which is why the two get used interchangeably even though the marks belong to different bodies.
Both are drawn as arcs radiating from a point, which is why they are confused. The Wi-Fi mark fans upward from a dot at the base and indicates a wireless network. The contactless mark lies on its side, opening to the right, and indicates that a card or terminal supports tap payment. Orientation is the reliable tell.
Both are two strokes meeting at a point above. In a keyboard shortcut the chevron is the control key, which is why documentation writes control-C as caret-C. At the front of a regular expression the same mark anchors the pattern to the start of a line, and inside a bracket expression it negates the set instead.
There is no single answer, and that is the finding. Some platforms draw do-not-disturb as a crescent moon and dark mode as something else; others do the reverse. A circle crossed by a horizontal bar is more reliably do-not-disturb. A crescent in a status bar genuinely cannot be read without knowing the platform.
In front of a figure it is currency. At the end of a regular expression it anchors the pattern to the end of a line. In a shell it introduces a variable. Nothing about the S-with-a-stroke distinguishes them, and shell scripts routinely contain all three uses within a few lines of each other.
Look for the person. A figure bending to an arc of water marks a fountain — a place to drink. A tap or glass without a figure states that the water is potable, which is a claim about the water rather than a direction to a facility. A tap can be marked potable without there being anywhere to drink from it.
The typographic ellipsis is a single character meaning words have been left out. The spread operator is three separate full stops that expand a collection into its elements. They render almost identically, so an ellipsis copied from a document into code does not parse — a genuinely confusing failure, because the line looks correct.
Both register approval and usually add the item to a list. Several large services replaced a star or a thumbs-up with a heart on the reasoning that a heart is a lighter, less judgemental gesture — a change in what people are willing to press, not a change in what the shape means.
The glass and fork means the material is safe to touch food. It says nothing about heat, and a food-safe container can still melt or leach in a microwave. Wavy lines mean the maker considers it microwave-safe — which is not a certification, because no body defines that mark. If it matters, the manufacturer's instructions are the authority, not the symbol.
In a filename pattern the star stands for any run of characters. In a regular expression it does not stand for anything: it repeats whatever came immediately before it, zero or more times. So the glob pattern for 'anything' is a bare star, but the regular expression for 'anything' needs a dot before it. Reading one as the other is a real and consequential error.
The hamburger is three plain stacked lines on screen and opens the main navigation. The menu key is a physical key, drawn as a small panel of lines with a pointer beside it, and opens the context menu for whatever is selected — the keyboard equivalent of a right-click. The shared stacked-lines motif is the only thing they have in common.
Vertical is the kebab, horizontal the meatball. That is the whole distinction, and it is a distinction in drawing rather than in meaning: both open a menu of secondary actions, and which one a product uses is house style. The food names are designer folklore, not terminology anybody defines.
Look at which strokes slant. The musical sharp has upright verticals and horizontals that slant slightly upward; the number sign is the other way round, with slanted verticals and level horizontals. They are separate Unicode characters — U+266F and U+0023 — and text search, sorting and filenames all treat them as different.
The character is one thing; what reads it decides the meaning. Before a word on social media it makes a tag. Before a numeral it means 'number'. At the start of a line in a shell script, Python or most configuration formats it means everything after it is a comment and is ignored. A hash inside a string is none of these.
As punctuation it ends an interrogative sentence. In code it opens a three-part choice: a condition, then the value if true, a colon, then the value if false. The colon is the tell — a question mark with a colon later on the same line is an operator, not a question.
Look at whether the arrow closes on itself. Refresh is a loop — the arrow chases its own tail — and repeats a fetch. Redo is an open arc that steps forward through a history of changes, reinstating what undo reversed. Pressing the wrong one is a recognised and irritating mistake.
This is a genuine ambiguity in the convention rather than a misreading. A rectangle with an arrow leaving through its top edge means 'share' on some platforms and 'upload' on others, and nothing about the drawing settles which. The share icon's other form — three dots joined by lines — is unambiguous, and the arrow-into-a-tray upload icon likewise; the collision is only between the two box-and-arrow drawings.
A shebang starts with the same hash that marks a comment, followed by an exclamation mark, and it must be the very first two bytes of the file. The kernel reads it to find the interpreter; the interpreter then reads the same line as an ordinary comment and ignores it. A blank line before it makes it only a comment, and the file will not run as intended.
Look underneath the arrow. No bar is shift, which applies only while you hold it. A bar is caps lock, which latches until you press it again. That single stroke is the difference between a momentary modifier and a latching one, and it is easy to miss at the size these are printed on a key.
The shift key is an outlined arrow with a stem and a broad head. The control key is a bare chevron with no stem at all — two strokes meeting at a point. Both point upward and both are modifiers, which is the whole of the resemblance; they do entirely different things and appear in different positions in printed shortcuts.
In code, three dots before a value expand it into its elements. In an interface, three dots in a row open a menu of further actions. Both are described as 'three dots' by the people who meet them, which is the entire basis of the confusion — there is no relationship between the two.
Count the bars. The tab key's arrow has a bar at the head and another at the tail. The end key's has one, at the head only. Both read as travel arrested at a boundary, which is why they are mistaken for each other on keyboard legends — but tab moves between fields and end jumps to the end of a line.
As a typographic mark the vertical bar separates alternatives or delimits a table column. Between two commands in a shell it connects the first one's output straight to the second one's input, so data flows through a chain without ever touching a file. Documentation calls both 'the pipe character', which is where the conflation comes from.
Alpha is a Greek letter and stands for a quantity — an angle, a coefficient, a significance level. The proportionality sign is an operator and stands between two quantities to say they keep a constant ratio. The drawings differ in that the proportionality sign's right-hand stroke runs out in an open curve rather than closing into the letter's tail.
The becquerel counts nuclear decays — one per second — and says nothing about harm. The sievert weights absorbed energy by the kind of radiation delivering it, and so estimates biological effect. A becquerel of one isotope and a becquerel of another can carry very different risk, which is exactly why exposure limits and medical doses are stated in sieverts and never in becquerels.
Look at what follows. A prefix never stands alone — it is glued to a unit symbol, as in kW or kg. A constant stands by itself in an equation. Careful physical writing subscripts the constant as k_B for exactly this reason, and the kelvin's capital K is a third claimant to the same letter.
Check the letter after the degree sign. C is Celsius, on which water freezes at 0 and boils at 100. F is Fahrenheit, on which the same points are 32 and 212. The scales coincide at −40 and nowhere else, so a number without its letter is genuinely ambiguous — and at everyday temperatures the same figure means very different weather.
A change of one kelvin and a change of one degree Celsius are exactly the same size, so a temperature *difference* may be stated in either. The scales start in different places: 0 K is absolute zero and 0 °C is the freezing point of water, 273.15 K. The written forms differ too — the kelvin takes no degree sign, so 300 K is right and 300 °K is not.
The degree sign is the discriminator, and it is the thing plain text loses. °C is a temperature and needs its preceding degree sign and a space before the number; italic c is a speed and stands alone in an equation. Where formatting is stripped — a filename, a search box, a plain-text note — they become indistinguishable.
Two short parallel lines. Between atoms in a structural formula they are a double bond — two shared electron pairs. Between quantities they assert equality. There is no visual difference at all, and none is needed, because the two never appear in the same expression.
Count the shafts and look at the heads. Equilibrium is two separate half-headed arrows pointing opposite ways: two real species interconverting, both present. Resonance is one shaft with a full head at each end: one species that neither drawing captures. Reading resonance as equilibrium claims two substances exist where there is only one.
The logical arrow has a doubled shaft and joins two statements that hold in exactly the same circumstances. The chemical one has a single shaft, joins two structural formulae, and means something stranger: neither structure exists, and the real molecule is a single thing no drawing captures.
Look at the shaft and at what surrounds it. Logical implication is drawn with a doubled shaft and sits between statements; a reaction arrow has a single shaft and sits between chemical formulae, usually with conditions written above and below it. Neither is an equals sign, and both assert direction rather than equality.
A capital K is the kelvin, a unit of temperature. A lower-case k is the prefix kilo, meaning a factor of one thousand and never standing alone. So kW is a kilowatt and KW is not a real unit symbol at all. NIST's guide lists exactly this kind of case error among the standard mistakes in applying the SI.
They are the same character, and that is the point. The catalogue records the letter itself and its use as a physical quantity separately, because a reader arriving from a physics equation wants wavelength and a reader arriving from an alphabet wants the letter. In physics the same λ is also the decay constant, and in linear algebra an eigenvalue.
They look the same and are not the same. The micro sign is U+00B5 and is the SI prefix meaning one millionth; the Greek small letter mu is U+03BC and is a letter used for a coefficient of friction, a population mean, and much else. Text search, sorting and string comparison treat them as different characters, which is why a document can appear to contain a term it cannot find.
If it sits after a number on a circuit diagram, a resistor or a rating plate, it is the ohm — a unit of electrical resistance. If it appears in a formula as a variable, it is the Greek letter, most often angular velocity in its lowercase form ω. The characters are visually identical in capital form, so position is the whole answer.
Case decides it. Lowercase σ is a variable — standard deviation in statistics, stress in engineering. Capital Σ is an operator: it instructs you to add a series up, and will normally carry limits above and below it. If it has an index underneath, it is the summation sign.
Biodegradable is close to meaningless on its own: almost everything degrades eventually, and the claim names no timescale and no conditions. Compostable states both. That gap is why unqualified biodegradability claims are restricted in several jurisdictions, and why a compostable mark is worth more than a biodegradable one.
CE covers the European Economic Area; UKCA covers Great Britain. Both are the manufacturer's own declaration that a product meets the requirements applying to it, and for most product categories nobody grants or checks them. Neither is a safety certification or a mark of quality, which is how both are widely read. UKCA's territory is Great Britain rather than the whole United Kingdom, because Northern Ireland follows the EU regime.
The EU energy label is mandatory and comparative: it grades a product on a lettered scale shown as coloured arrows, so two labelled products can be ranked against each other. Energy Star is voluntary and a threshold: a product either qualifies or does not, and the mark gives no indication of the margin. A product carrying both is making two different kinds of claim.
Look at what the loop is drawn on. On a container it marks a place: put recyclable waste here. On packaging it makes a claim about the material itself — and, notoriously, a bare loop is not a promise that the item is collected for recycling where you live. One is a direction; the other is an assertion about a substance.
The Green Dot tells you nothing about whether the packaging can be recycled — it only means the producer paid into a packaging-recovery financing scheme. The three-arrow recycling loop is the one that makes a recyclability claim. Two interlocking arrows in a circle is the Green Dot; three chasing arrows in a triangle is the recycling symbol.
Check for a number. The bare loop claims the item is recyclable — something you can do with it in future. The same loop with a percentage claims how much recycled material it already contains — something already true about it. Forward-looking versus backward-looking, in the same graphic.
Look for a number. Chasing arrows with a numeral inside are a resin identification code: they say which plastic the item is made of and promise nothing at all about whether anyone will collect it. Chasing arrows with no numeral are the Mobius loop, which does assert recyclability. The codes borrowed the arrows, and that borrowing is why the mistake is universal.
These route to different places and are not substitutes. The recycling loop means the material can be reprocessed into new material. The Seedling means the item is certified to break down in an industrial composting facility — not in your garden compost, and not in recycling. Composting certified items in the recycling stream contaminates it, and vice versa.
They give opposite instructions about your household bin. The three chasing arrows say the material is generally recyclable. The crossed-out wheeled bin says this item must not go in general waste at all and has to be taken to a separate electrical-waste collection point — it is a legal requirement, not a recycling suggestion.
One is certified, the other is a claim anyone can print. The Seedling means EN 13432 compostability verified by an independent certifier. A generic leaf or sprout labelled 'biodegradable' means only that the material will break down eventually — with no defined timeframe, no defined end state, no standard and no verification.
The seedling certifies industrial compostability, which needs sustained high temperatures a garden heap never reaches. The home compostable mark certifies the much harder domestic case. An item carrying only the seedling put on a compost heap at home will still be there next year, which is why treating the two as interchangeable matters.
They ask for the same behaviour but are different marks with different owners. The Tidyman is a UK trademark of the charity Keep Britain Tidy. The do-not-litter pictogram is ISO 7010 M030, a brand-neutral international standard, and appears as a white figure on a blue circle. Neither says anything about recyclability.
Look at where you are. On a package, a figure putting litter into a bin is the tidyman, which is a courtesy request and not a recycling claim. On a screen, a bin on its own is a delete control. Neither has anything to do with the other, and the tidyman in particular is routinely misread as meaning the packaging is recyclable.
They use the same crossed-out wheeled bin. Look underneath it: chemical letters (Hg, Cd or Pb) mean it is the battery mark; a plain bar, or nothing, means it is the WEEE mark for electrical equipment. Both instruct separate collection rather than making any recyclability claim.
Context decides. On a drawing, before a number, it is a diameter. In mathematics, standing alone, it is the empty set. They are separate Unicode characters (U+2300 and U+2205) and both are routinely typed as the Scandinavian letter Ø or a slashed zero, neither of which is either of them.
Count the horizontal strokes. One assigns a value. Two compare after converting types, which is where surprising results come from. Three compare without converting, so a string and a number are never equal. Miscounting is among the most common mistakes made by people new to the language, and nothing in the shape warns you.
The wide end always faces the larger quantity and the point faces the smaller one — that single rule settles both signs at once, and every mnemonic taught for them is a restatement of it. Thomas Harriot introduced the pair together in a work published in 1631, ten years after his death.
Between two quantities it compares. After a command it sends that command's output into the named file — and truncates the file first, discarding whatever was there. That truncation is the part that surprises people, and doubling the character appends instead of replacing.
Count the arrowheads. A single head means implication: if the left statement holds then so does the right, with no claim in the other direction. Two heads mean equivalence: each statement implies the other, so they hold in exactly the same circumstances. Reading a one-way implication as though it were equivalence is the commonest error made with either symbol.
In logic it asserts that the right-hand statement follows from the left-hand one. In JavaScript the same arrow separates a function's parameters from its body. Both are drawn as two horizontal strokes followed by an angle bracket, and the notations are otherwise unconnected.
Union is the cup, opening upward, and gives everything in either set. Intersection is the cap, opening downward, and gives only what is in both. The spoken names 'cup' and 'cap' exist precisely because the drawings are so easily reversed — reading a formula aloud disambiguates it in a way looking at it does not.
Look at whether the stroke is sharp or curved. The less-than sign is a wedge of two straight strokes meeting at a point and says one number is smaller than another. The subset sign is a single curved stroke and says every member of one set is also a member of another. They are different characters about different kinds of thing, and only typography keeps them apart.
Between two quantities it is a comparison. After a command in a shell it redirects input: the command reads from the named file instead of from the terminal. The meanings are unrelated — the shell use is not 'less than' anything — and only position tells you which you are looking at.
− subtracts, or marks a negative value. ± means 'give or take' — a tolerance, a margin of error, or both roots of a quadratic. A measurement written 20 ± 2 spans 18 to 22; written 20 − 2 it is simply 18.
Context decides entirely, because the glyphs are identical. Between two numbers it multiplies. In the corner of a panel it closes it. Beside an answer it marks the answer wrong. Nothing about the shape distinguishes the three, and the interface use carries its own ambiguity: the same mark rejects a value and dismisses the panel containing it.
One plus sign adds two things and produces a result. Two plus signs add one to a variable and store it back, changing the variable itself. The distinction is not addition versus addition-by-one; it is producing a value versus modifying one, and the doubled form is routinely misread as ordinary arithmetic.
Lower-case pi is the constant, approximately 3.14159, and stands for a value. Capital pi drawn large is the product operator: an instruction to multiply a sequence of terms, taking an index and limits exactly as the summation sign does. They are separate characters and separate ideas, related only by the alphabet — the same relationship sigma has to the summation sign.
Look at the left-hand edge. A straight flat back is an AND gate: the output is true only when every input is. A curved concave back is an OR gate: true when any input is. Everything else about the shapes is similar, which is why the back edge is worth checking deliberately rather than at a glance.
Equal-length lines mean a capacitor. Alternating long and short lines mean a battery, with the long line positive. If the second line is curved rather than straight it is a polarised capacitor — still a capacitor, but one that must be fitted the right way round.
Look at the pattern. Even short dashes throughout is a hidden line: an edge that exists but is concealed behind material. Long dashes alternating with dots is a centre line: an axis of symmetry or the centre of a circle, which is not a physical edge at all. Reading a centre line as an edge is the commonest beginner's error on a drawing.
The symbol is a section through the hole. A flat-bottomed bracket calls for a counterbore: a cylindrical widening for a bolt head with a flat underside. A shallow V calls for a countersink: a conical widening for a tapered screw head. Match the shape of the symbol to the shape of the screw head and it is unambiguous.
Look for two small parallel arrows beside the triangle. Pointing away means light leaves the component, so it is an LED. No arrows means a plain diode. Arrows pointing towards the triangle mean something different again — a photodiode, which detects light rather than emitting it.
They are alternatives, not a pair. The double square means the appliance is protected by double or reinforced insulation and needs no earth connection, which is why it can legitimately have a two-pin plug. The earth symbol marks a terminal that must be connected, because that appliance relies on earthing instead.
Look at which side the circles are on. In the first-angle symbol the end view sits to the left of the cone; in third-angle it sits to the right. That mirroring is the whole message: the two conventions place every view on opposite sides, so a part made from a drawing read under the wrong convention comes out mirrored. Which applies is stated on the drawing precisely because it cannot be guessed.
Look for a line running through the rectangle lengthwise: that is a fuse. A bare rectangle is an IEC resistor. If the diagram uses North American conventions the question does not arise, because its resistors are drawn as zigzags instead — so identify the convention first, then read the component.
Look at the circle. A circle with a gap and a line crossing it is standby — the device stays connected to its supply. A closed circle with the line inside is a true on/off toggle. A plain circle with no line at all means power is actually disconnected. Most consumer 'power buttons' are the standby symbol, which is why unplugging still matters.
Check where the dot sits. A dot immediately to the right of the notehead adds half the note's value again — a dotted half note lasts three beats. A dot directly above or below the head means staccato: play it short and detached. One dot, two opposite instructions, and only position distinguishes them.
They occupy the same place and are read the same way. A C means four-four; two stacked numerals state any metre explicitly. The C is not an abbreviation of the word 'common' — it descends from a broken circle used in medieval notation to mean imperfect time, and a full circle meant threefold time.
Length is the tell. A crescendo hairpin is drawn long, below a stave, and spans the passage it applies to — its extent *is* the instruction. A less-than sign is one character wide and sits between two values. If it stretches, it is music; if it fits between two numbers, it is mathematics.
Look at the head. A hollow oval with a stem is a half note lasting two beats; a filled oval with a stem is a quarter note lasting one. Nothing else differs — same stem, same position, same everything — and at small print sizes the fill is easily lost, which is why this is the distinction beginners miss most often.
Look at the line. A rectangle hanging *below* the fourth line is a whole rest; one sitting *on top of* the third line is a half rest. The shapes are identical, so position is the only information — and a whole rest means a whole bar's silence whatever the time signature, which makes it the one rest whose length is not fixed.
Look at the two notes the curve joins. Same pitch means it is a tie: they become one sound of combined length and the second is not played again. Different pitches mean it is a slur: play them smoothly as one gesture, but play them all. The curve is identical in both cases, so the pitches are the only evidence.
A single C in a circle asserts copyright. Two C shapes mark a Creative Commons licence — which grants specific permissions while the creator keeps their copyright. A CC badge does not put a work in the public domain, and it does not tell you what you may do on its own: the condition marks beside it carry the terms.
© covers creative works and generally applies automatically on creation. ™ and ® both cover brand marks, but ™ asserts an unregistered claim anyone may use, while ® is legally restricted to marks actually registered with a trademark office — using ® without registration is unlawful in many jurisdictions.
Between two quantities, two level strokes assert that they are equal. Enclosed in a circle on a licensed work, the same two strokes are the no-derivatives condition: the work may be shared, but modified versions may not be distributed. Adapting it privately is not restricted — the condition is about sharing the result.
Both stand for permissions being passed on: anything built on the work carries the same freedoms. The share-alike mark is an actual licence condition and binds. The copyleft symbol is a reversed C that names the concept, is registered nowhere, and imposes nothing — a work is copyleft because of the licence it carries, not because of that badge.
The set-membership sign says a thing belongs to a set and sits between two expressions. Epsilon is a Greek letter naming a quantity, most famously the arbitrarily small tolerance in the epsilon–delta definition of a limit. They are distinct characters; the membership sign is drawn with a longer, straighter middle stroke and is used as a relation rather than as a value.
They are not variants of each other. # is the number sign — hash, hashtag, and the 'pound key' on a North American telephone keypad. £ is the pound sterling currency sign, from the Latin libra. The only thing they share is the word people say out loud.
§ cites a section; ¶ marks a paragraph. If you are pointing at a numbered division of a statute or contract, you want §. If you are pointing at a block of prose — or looking at the mark your word processor shows when formatting is visible — you want ¶.
In astronomy the crescent stands for the Moon. In an interface it usually switches to a light-on-dark colour scheme. But not always: several platforms use the same crescent for do-not-disturb, so a crescent in a status bar cannot be read at all without knowing which system you are looking at.
On a chart or in an ephemeris, a circle with radiating strokes is the Sun itself. On a shipping carton the same drawing is an instruction: keep this package out of direct sunlight. One names a star, the other tells a handler where to put a box, and only the surrounding context separates them.
Read the letter. P or F inside the circle permits professional dry cleaning with a named class of solvent. W permits professional wet cleaning, which is a controlled water-based process. They are opposites, and a garment may carry a crossed-out washtub — do not wash at home — while still permitting professional wet cleaning.
Look at which way the line runs. Vertical means hang the garment to dry. Horizontal means lay it flat. The difference matters most for knitwear, which stretches out of shape under its own weight when hung wet — and the two marks are otherwise identical, which is why the instruction is so easily misread.
A red ring with a diagonal bar forbids the thing shown. A solid blue disc requires it. So the same pictogram of a person means 'do not enter' in red and 'this way only' in blue. If the circle is filled it is an instruction; if it is an outline with a bar through it, it is a prohibition.
Shape and setting decide it. A yellow triangle on a wall or a machine is the general safety warning sign: a hazard is present, unspecified, so read the text beneath it. A red-bordered diamond on a product label is the GHS pictogram, which is not vague at all — it stands for a defined set of chemical hazard classes such as skin or eye irritation.
Look for the circle. The seatbelt reminder is just a seated figure with a diagonal belt, and goes out when everyone buckles up. The airbag/SRS light adds a large circle or oval in front of the figure representing an inflated airbag — and it does not go out, because it signals a fault that may stop the airbags deploying in a crash.
Go by colour. The red brake-system light can mean a serious hydraulic fault affecting your ability to stop, and warrants stopping safely and checking. The amber ABS light usually means only the anti-lock function is affected, with ordinary braking still working — but get it checked, because you have lost skid protection.