Maybe it's too late, but...
Black & White 2 is said to be inferior to Black & White, but it looks a LOT nicer.
I'm not very good at the games and haven't played them for ages, so I can't offer much, but...
B&W simply had you impressing villages with your godly powers + your creature, whether you use nice miracles and water their trees or not so nice miracles and burn their houses. All to build your influence and take over each island. Your creature's AI is supposed to be ridiculously smart and you can teach it how to treat its surroundings, and how to use miracles by itself. It's massively reactive to your actions. For example, if you use a certain miracle a lot and your creature sees it, it may eventually learn how to use the miracle itself. I always taught my creature to throw fireballs at my own village and promptly have virtually no influence as my only village burns. xD
Though it's pretty old and it definitely shows in the graphics, if you care for that sort of thing.
B&W2 looks a lot nicer, but training your creature is kind of dumbed down and simplified compared to the first game. It's a little different in terms of mechanics, too. To play the game in the 'good' way, you build your city to be as impressive as possible, and people will be convinced to move to your city until everyone on the island is within your influence. To play in the 'evil' way, you have to build armies and take the villages by force. I think people dislike B&W2 because it's less god game and more RTS, but that might appeal to you. Miracles are still there, but they seemed to be a bit of a secondary thing to me.
It also added a currency system called Tribute, which is required to obtain new powers and build new kinds of buildings. I can't remember how you got new stuff in B&W1, but there definitely wasn't a currency system. It might have been that certain villages give you new things, but again, not sure. What made me sad was that to teach your creature new miracles, you just buy with Tribute...
Plot-wise, B&W1 has you fighting other Gods, while B&W2 has you fighting the Aztecs as the only surviving God. Both games feature your 'conscience' talking to you, a tiny devil dude and a tiny god dude. Their dialogue between each other and to you is hilarious. xP
I think that's about everything I can dig up. Remember that my memory sucks and a few details may be wrong, so take with a grain of salt :b
