Idea #14 - Metaphor/Metonym

The other day I was trying to understand contemporary art better and I came across a discussion board about the differences between modern and post-modern art. They said that a big difference is that modernism tends to use metaphors, where post-modernism uses metonymy. I knew that a metaphor is something that is meant to represent something else. For example, a staircase could be a metaphor for life. I am still trying to understand metonymy but my understanding is that a metonym for life could be something like a human or animal, something associated with life. A metonym is more of an association where metaphor is a similarity. After learning this, I'm still not sure how this applies to visual art, I think I get it as far as verbal use, but when it comes to either in art I have trouble understanding what the metonym/metaphor is referencing and differentiating between the two. That is, even knowing this, I still can't differentiate between modern and post-modern art. It seems like modern art is more non-representational, which makes me think that the abstraction is the metaphor. I might be thinking too into it, maybe I shouldn't worry about what is what and just use what I need to use to convey my message.