3G/Wifi Vita - has a built in "always on" network (3G), provided you want to pay extra for it. It also has a built in GPS for location services (Near, Maps, etc). Can also utilize wifi networks.
Wifi Vita - can only connect online while in range of a wifi network. Uses wifi information for location services (Near, Maps, etc).
Other than that, they are the same, exact thing.
I laugh at the 3g version. I carry my phone everywhere so I simply use it as a hotspot whenever I want to play online. I can do that anywhere and no extra charges for more 3g.
Tis true, but people like me...i dont have a smart phone, just a cheapy prepaid phone, with no apps or extra services, just phone calls and texts, so wifi is great, but i wouldnt be able to use it from my phone, hence 3g is my option besides finding a hotspot.