A simile is a figure of speech in which two unlike things are explicitly compared. Although similes and metaphors are sometimes considered to be interchangeable, similes acknowledge the imperfections and limitations of the comparative relationship to a greater extent than metaphors.
To help you identify a simile versus a metaphor, know that the words “like” or “as” are typically used in a simile.

As like as not = probably

Avoid like the plague = to shun, or evade if at all possible

Bleed like a stuck pig = to bleed profusely

Breed like rabbits = to breed very rapidly, to have many children

Cry like a baby = cry a lot

Cut like a knife = to sting severely, to be very sharp

Drop like flies = die en masse, one after the other

Drink like a fish = to drink alcohol heavily and in excess

Eat like a bird = to eat in small amounts rather than in a single full meal

Eat like a pig/eat like a horse = to chew noisily, with one's mouth open, or with much greed

Fit like a glove = to be a perfect fit, to be exactly the right size

Float like a butterfly = to move effortlessly and in an agile fashion

Get on like a house on fire = to immediately start a good relationship with someone

Go down like a lead balloon = to be received negatively by others

Go out like a light = to fall asleep quickly

Grin like a Cheshire cat = to smile broadly, especially in a self-satisfied way

Have a memory like a sieve = to have a poor memory; to have difficulty remembering things

Kick like a mule = to have a very strong physical effect

Laugh like a drain = to laugh with a loud, coarse sound

Laugh like a hyena = to laugh hysterically

Leak like a sieve = full of holes

Light as a feather = extremely light, having minimal weight

Like a cat on a hot tin roof = jumpy, nervous

Like a lamb to the slaughter = helplessly and innocently, without knowing the unpleasant consequences

Like a ton of bricks = very strongly; very heavily; often unexpectedly

Like feeding time at the zoo = extremely frenetic, disorderly and messy

Like death warmed over = Ill, unwell

Like crazy = to a great or excessive degree; with great speed, output, enthusiasm

Like clockwork = with perfect regularity and precision; faultless

Like chalk and cheese = two things that are different

Like a train = with unstoppable momentum

Like a man = bravely, decisively and without complaining

Like a million dollars = extremely good or well

Like a kid in a candy store = elated or excited as a result of having many options to choose from

Like a duck takes to water = very naturally; without effort

Like a dog with a bone = stubborn; persistent; relentless

Like a dog on heat = very energetic and enthusiastic

Like a charm = very effectively

Like a bump on a log = idly, listlessly, or uselessly

Like a bull in china shop = clumsy, aggressive, without care or concern, without self-control

Like a bear with a sore head = very irritable; bad-tempered

Like hot cakes = quickly, especially by purchase or consumption

Like nobody's business =rapidly; excessively; like crazy

Like rats from a sinking ship = away from a failing project

Like riding a bike = said of skill that, once learned, is never forgotten

Like shelling peas = repetitive, but very easy

Like shooting fish in a barrel = extremely easy

Like taking candy from a baby = easy to achieve

Like the back end of a bus = very unattractive

Like the clappers = very hard or very rapidly

Like the wind = quickly, at a high speed

Like turkeys voting for Christmas = serving to bring about a situation detrimental to the person performing the action

Like water off a duck's back = without immediate or lasting effects

Like white on rice = inseparable; in very close proximity; following closely

Out like a light = asleep or unconscious

Quack like a duck = to appear to be exactly what one is

Read like a book = to be able to discern someone's thoughts from his or her body language or other behaviour

Run around like a chicken with its head cut off/run around like a headless chicken = to act in a haphazard or aimless way; to act frantically or without control

Run like a top = to operate smoothly

Run like the wind = run very quickly

Sing like a bird = to have a beautiful singing voice/to reveal secrets

Sink like a stone = to completely fail

Sleep like a baby = sleeping soundly

Swear like a trooper = to swear a lot; to utter many swear words

Sweat like a pig = to sweat profusely, to be perspiring lots of sweat

Swim like a fish = to be a very strong swimmer

Watch like a hawk = to observe closely and keenly