If theyre just different models of the same base camera. The newer one should have more improvements. With cameras its best to buy the newest so youll be prepared. Why are you buying Sony's though? For the price of one of those you can get a nice DSLR. Or do you need a DV camera for school? Keep in mind though that neither of these cameras record in 24fps I believe.
Or if your going to use this for skateboarding just buy a DSLR and buy a fisheye lens.