Whoa... they're SO different... US kind of gives me a YA paranormal vibe, and I really like it... but the AU one is confronting and cool... Without knowing what the book is about, I don't know. After just reading the blurb on Amazon, I think the AU cover does a fab job at channeling what the book sounds like. If I saw it in a store, I'd pick up the US cover thinking something like a Julie Kagawa book or Shive by Maggie Stiefvater, then be confused.
@ Sarah (Saz101) I actually own the American one and it looks all glittery on the cover, what that has to do with anorexia/bulimia I have no idea, but I know what you mean about it looking like a paranormal type cover that's what I thought it was the very first time I saw It.
@ Roro I prefer the American one too