Which best identifies a metaphor

A metaphor is used to compare two things without using the words 'as' or 'like' in the sentence.

Example: He is such a pig - that sentence compares two things the boy and the pig and no words such are mentioned with 'as or like' therefore it is a metaphor

A metaphor is a figure of speech used to compare 2 things without saying similes such as, like, etc. Metaphors are mostly used in poems.