A simile is a comparison between two unlike things, usually using the words "like" or "as."The presence of these two words tends to make similes easy to identify on a test. "Life is like a box of chocolates. You never know what you're gonna get." - Forrest Gump.
Metaphor is a figure of speech frequently taught alongside simile to help illustrate the differences between the two words.
Personification is the attribution of human qualities to non-human things. These can be objects, events, ideas, or even living, non-human things.
Metonymy is a slightly more difficult term to explain. It is a figure of speech in which a thing is referred to not by its own name, but by the name of something closely related to it. This idea can best be clarified through a couple of examples.F.e:The "pen" stands in for "the written word"