BB/VW1 was basically B/W1 redone to be more difficult, enable the player to catch all pokemon in one game, and has various changes to some pokemon themselves, (movesets/typings/bp of moves) alot of which are things that fans considered should have been done originally, such as Emboar being a Fire/Dark type.
I'd assume BB/VW2 would have similar changes. --- Maybe I AM a flip-flopper. I'm also a schizophrenic. What's your excuse?