I believe you mean SIMILE.
Both are figures of speech. The difference between simile and metaphor (simply), simile shows a direct comparison, metaphor shows an indirect (assumed) one... (I'm confusing myself here, but hopefully my examples will be of help)
Simile: She walks in beauty, like the night.
Metaphor: The mind is an ocean. This city is a jungle.
(Both examples are taken from Cambridge Advanced Learner's Dictionary.)
(Tip: If a comparison is stated, or implied and the word 'like' is used, it's a simile, otherwise it's a metaphor)