The only real difference is the 1080x30fps and the 720x60fps modes. Unless you are planning on doing DVDs from your recordings 1080p is overkill for the internet. The 60fps is good if you are doing a lot of slow motion editing, otherwise, again, it is overkill.
But having said that, if I were to buy another one I would probably get a 1080p just to try out some slow motion editing. Don't get me wrong 30fps you can still do slow mo and it looks great, just with 60fps it can look a lot smoother.
If you are ona budget then the 720p is a better option andyou can spend a little bit more on some great accessories for it.