besides the obvious that the 520i is the international version and the 520a is for N.A.? ie.are menus different,capabilities different, etc. i can find both versions online but have yet to see any difference between the two. maybe i am missing a minor difference, yet a very important one. i mean, there must be something otherwise se wouldn't sell different versions...would they?
There is actually a 3rd version too, one for the Asian market. I don't think there is a difference at all between the 3 phones, and not sure why SE made 3 and not 1. My only guess is the language associated with each, the 520a may just have English, while the 520i has multiple languages. There all quad band so it shouldn't matter what version you get, its going to work regardless.