Like are there pokemon that will only be on black 2 or white 2
The only known difference is that the mascot of Black 2 is Black Kyurem and the mascot of White 2 is White Kyurem. This likely means that they are version specific to their game, although even this is not certain. Whether this means the other will not be able to be obtained in the other game in a way other than trading is not known, as the means of obtaining these two Kyurem is not yet known.
the differences in pokemon are here
location differences :
there is a cave which has water in black 2 and lava in white 2
black city and white forest return,route 4 is developed with it being in ruins in white 2 and modern look in black 2 and opelucide retains the modern look fom black and olden look from white.