How can one differentiate between a simile and a metaphor?
The definition of a metaphor is...
...an implied analogy or unstated comparison which imaginatively identifies one thing with another.
In other words, two dissimilar things are being compared as if they were the same, however what they share are simply the same characteristics, and "like" or "as" are NOT used in the comparison. I was once told to think of a metaphor as X is Y. You may recall the famous song lyrics:
You are the sunshine of my life.
"You" is X and "sunshine" is Y. "You" is not literally "sunshine," but "you" may have the same characteristics of the sun: being warm, brightening up one's day, helping someone find his or her way in a troubling time, etc., as the sun aids us in navigating throughout our world each day. The subject of the song ("you") is not hot to the touch or too bright to look at without sunglasses. And while the reader may not know "you," he or she can imagine what the subject is like in bringing to mind the positive characteristics of the sun.
Robert Herrick uses a metaphor in his poem, "To the Virgins, to Make Much of Time."
The glorious Lamp of Heaven, the Sun,
The higher he’s a getting... (5-6)
Herrick is saying that the sun is a lamp in the heavens. (X is Y.) A metaphor, as you can see, is a figure of speech—also called "figurative language;" it should not be taken literally. Figurative language is commonly used in poetry: metaphors are very popular with many poets.
The simile is defined as...
...a figure of speech in which two things, essentially different but thought to be alike in one or more respects, are...
(The entire section contains 566 words.)
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The most recognizable difference between a simile and a metaphor is the choice of words in making the comparison. Similes utilize the words "like" or "as" when making the comparison, as in "Her eyes were as bright as stars". On the other hand, a metaphor makes the comparison without either of these words, in which case the sentence would read as "Her eyes were stars".
Informally, I personally think of two other differences between similes and metaphors. Similes, since they use the words "like" or "as", allow more room to specify exactly what aspect is being compared (in the above example, brightness), whereas metaphors are a bit more up for interpretation depending on what two objects are being compared. However, metaphors also give off the air of being firmer because they are saying that one object is the other, not just similar. While of course this would (in many cases) be impossible, the strength of the sentence seems to cement the comparison better.