What are examples of metaphor and simile?

"All the world's a stage" is a metaphor (Shakespeare, As You Like It, 1599). "My love is like a red, red rose" is a simile (Burns, "A Red, Red Rose", 1794). Both lines compare one thing to another; the only difference at the surface is whether the writer attaches like or as to flag the comparison. What makes the question worth a page is that the same idea can be written either way, and the two figures don't carry the comparison the same distance. Burns could have written my love is a red, red rose and meant something the simile refuses to mean.

How does the same idea read as a metaphor vs. as a simile?

Put the same idea in both shapes and the choice between the figures stops being abstract. Each pair below takes one subject (love, life, time, a person, an act of violence) and shows what a writer commits to when the comparison is asserted versus flagged.

Idea	Metaphor (sourced)	Simile (sourced)	What changes
Love	"My love is a fever, longing still / For that which longer nurseth the disease" (Shakespeare, Sonnet 147, 1609)	"My love is like a red, red rose / That's newly sprung in June" (Burns, "A Red, Red Rose", 1794)	The metaphor diagnoses love as a sickness. The simile invites the reader to picture one specific rose; the writer keeps a step back from claiming love is a rose.
Life	"All the world's a stage, / And all the men and women merely players" (Shakespeare, As You Like It, 1599)	"Life was like a box of chocolates. You never know what you're gonna get" (Forrest Gump, screenplay by Eric Roth, 1994)	The metaphor declares a frame and runs with it for seven ages. The simile makes one local observation and stops; you can extend it, but it doesn't ramify the way the stage does.
The bleakness of a life without dreams	"Life is a barren field / Frozen with snow" (Hughes, "Dreams", 1922)	"Hope is the thing with feathers / That perches in the soul" (Dickinson, c. 1861, pub. 1891)	Hughes asserts the equation outright. Dickinson formally hedges, but the figure is so closely held that some editors read her opening line as a metaphor where the simile flag has been dropped. The line is fuzzy.
Time	"Time is the longest distance between two places" (Williams, The Glass Menagerie, 1944)	"Time, like an ever-rolling stream, / Bears all its sons away" (Watts, "O God, Our Help in Ages Past", 1719)	The metaphor names time as a distance and lets the reader carry the idea where it goes. The simile fixes time to one specific image, a moving stream, and gives Watts the freedom to extend the picture across stanzas without claiming the equation outright.
A person's qualities	"Juliet is the sun" (Shakespeare, Romeo and Juliet, 1597)	"She walks in beauty, like the night / Of cloudless climes and starry skies" (Byron, "She Walks in Beauty", 1814)	Romeo's metaphor claims Juliet's identity, not her resemblance; the line refuses qualification. Byron's simile lets him be specific about which night, which sky, with precision the metaphor would refuse.
An act of violence	"The air is a mill of hooks" (Plath, "Mystic", 1963)	"He felt his whole body as if it were a piece of stretched canvas, holding back something behind it" (Updike, Rabbit, Run, 1960)	The metaphor lets Plath claim a physical impossibility as the literal state of the air. The simile lets Updike specify the canvas and what it holds back; the reader sees the comparison being assembled.

The pattern is consistent: a metaphor asserts; a simile points. The simile is the safer figure for precision (the writer can specify which rose, which night) and the metaphor is the more aggressive one for claim-making (the writer can declare a thing is another thing and the reader has to hold them together).

How do you tell them apart in any sentence?

The working test is short. If the sentence flags its comparison with like or as, it's a simile. If it states the comparison without a flag, it's a metaphor. "Juliet is the sun" is a metaphor. "Juliet is like the sun" would be a simile.

The test breaks down in a few places, and these are the edge cases that trip readers up.

• "He runs like his father." Not a simile. Like is being used as a preposition introducing a literal comparison; the writer means he runs the same way his father does, not that running is one thing being compared to running. The figure requires the two sides of the comparison to be different kinds of things.
• "As the sun rose, the camp packed up." Not a simile. As introduces a temporal clause (when the sun rose), not a comparison. The figure needs as to mean in the manner of.
• "The leg of the table is loose." A metaphor, even without a verb. The body's leg has been carried across to furniture; the comparison is silent because the language has metabolized it. Dead metaphors still parse as metaphors.
• "Time is money." A metaphor, despite using is. The state verb does not flag the comparison; it asserts the equation flat. Most metaphors run through is, are, or no verb at all.
• "Her words cut him." A metaphor with a verb doing the carrying. Cut transfers from the literal action onto speech without a flag. The figure lives in the verb.

One sentence to keep: the figure is a simile when the comparison is flagged with like or as and the two sides are different kinds of things. Anything else with a comparison riding on it is a metaphor.

What does each figure do that the other can't?

The grammatical test sorts most sentences, but the meaning-level distinction is what tells a working writer which figure to reach for.

A metaphor asserts the comparison as a fact of the sentence. When Romeo says "Juliet is the sun" (Shakespeare, Romeo and Juliet, 1597), the reader is told to hold Juliet and the sun together as if they were the same object. The figure refuses the distance the word like would put between them. That refusal is what gives metaphor its force, and it's also why metaphor can ramify into extended structures: once the frame is asserted, the writer can keep working inside it. Shakespeare's stage in As You Like It runs seven ages long because the opening metaphor asserts that the world is a stage. Once that's asserted, every age the speech walks through is a scene in the same play.

A simile flags the comparison as a comparison. When Burns writes "My love is like a red, red rose" ("A Red, Red Rose", 1794), the word like tells the reader the writer knows roses and lovers are different kinds of things and is choosing to put them next to each other. The flag is a small concession of distance, and it buys the writer something the metaphor refuses: precision inside the comparison. Burns can specify red, red and newly sprung in June because the simile holds the two sides apart far enough that the rose can be described in detail without the figure breaking. A metaphorical "my love is a red, red rose, newly sprung in June" reads as overworked because the assertion is doing more than one job and one of the jobs is decorative.

Two consequences for a writer choosing between them:

• A metaphor is the right tool when the comparison is the point of the sentence and you want the reader to live inside the frame. The reader is supposed to feel the equation.
• A simile is the right tool when the comparison is illustrative and you want the freedom to specify. The reader is supposed to see what you're pointing at.

The same sentence can usually go either way. "Her voice is silk" and "her voice is like silk" both work; the choice is whether you want the reader to hold voice and silk as one thing or to see you placing them side by side.

Are similes a kind of metaphor, or a separate figure?

Scholars disagree, and have for two thousand years. Classical rhetoric treats simile as a species of metaphor. Aristotle, in the Rhetoric (3.4), calls simile a kind of metaphor differing only in form, distinguished by the explicit as or like that marks the comparison. Quintilian (Institutio Oratoria, 8.6) follows the same line: the figure is the comparative move; the flag is incidental. On the classical view, "my love is like a red, red rose" and "my love is a red, red rose" are two surface forms of the same underlying figure.

Most modern handbooks and stylistic references split them into two distinct figures. The argument is that the flag changes how the reader processes the sentence. A simile registers as a comparison and the reader holds both sides apart; a metaphor registers as an assertion and the reader fuses them. If the cognitive event is different, the figure is different. Both views are defensible and both are still in active use in the literature.

The practical test is the same either way: look for the flag. The disagreement is over whether the flagged figure is a subtype of the unflagged one or its own thing. Rhetogen treats them as distinct figures with overlapping work, because the reader who lands on this page is usually asking "is the line I'm reading a metaphor or a simile?", and that question only has a clean answer under the modern split. Once the test is in hand, the choice between the two figures stops being a grammar question and becomes a question about what the sentence needs to do. A metaphor claims. A simile points. Pick the one the sentence is asking for.