Holden would Kick Gatsby's ass
First thing I can think of is a comparison between the people and things Holden calls "phony" and Gatsby. It's been at least 10 - 12 years since I read either one of them, there might be something better, this is just the first thing I can think of.
Gatsby was completely white trash New Rich. He was Tacky and dressed badly (there is a section about him wearing some kind of woven gold lame' shirt). But, Gatsby was also living the American dream, and that's pretty much all he wanted. He needed to be phony, but it wasn't natural, and it showed thru.
Holden, on the other hand, comes from a pretty well off family, but that is not what he wants. He doesn't want to be rich or powerful or have people like/ respect him. All he wants is truth (his quest for non-phonyness).
Don't blame me if you get a bad grade.