Simile uses "like" or "as." Simile: He was as hungry as a bear. Metaphor: He was a hungry bear. Boom. Done.

Both are figures of speech. A 'simile' is when something is explicitly compared with something else. "He is as strong as a lion" "She is like the wind." " She danced as gracefully as a swan." "Shall I compare thee to a summer's day? Thou art more lovely and more temperate " (Shakespeare). Notice that the compared objects or persons don't necessarily have anything in common,yet they are directly linked with words such as 'like' ,'as' etc.. 'Metaphor' also being a figure of speech differs from the simile. In the case of a 'metaphor' a term or phrase is applied to something to which it is not literally applicable in order to suggest a resemblance. Here you don't explicitly use 'as' or 'like' to indicate resemblance. "He was a lion in the battle." "She is a graceful swan dancing on the floor." Here notice that it isn't an explicit likeness, the subject is rather identified by another object in order to refer to certain qualities it holds,that are very much similar to those of the object. She is a 'woman',but was identified as a 'swan' to refer to her graceful moves. 'Metaphors' is fundamental in poetry,in which its varied functions range from merely noting a likeness to serving as a central concept and controlling image.

oh it's hard to explain in few words