In pokemon Black and White there are many version exclusive pokemon, new and old. The caterpie tree is exclusive to White while the weedle tree to Black. Other pokemon are split up like this in these generations and up to the 5th. What really matters though are those split up exclusive to the 5th generation because any others could be traded from 4th generation games. These though are really a matter of personal preference as most of the PKMN split are of the same type and strength. There is a cotton PKMN in Black and a Bellossom-like one in White. In Black there is this Psychic type PKMN tree:
In White there is this Psychic PKMN tree that looks like green blobs:
There are also eagle PKMN in White while there are volture PKMN in Black. In Black there is a just flying type legendary while in White it is electric-flying. Finally in Black there is Reshiram (left, the white one) while in White there is Zekrom (right, the black one). Reshiram is dragon-fire type while Zekrom is dragon-electric type.