The primary difference is the location of the two villas relative to the other buildings and activity areas at the the Bali IC. My preferred one is the one located on the left hand side of the resort, by the 2000 wing. I believe the villa's number is 2136. The entire back of the villa is surrounded by tall bamboo, and is very secluded. There is hardly any foot traffic that comes near the villa, and it makes me forget that there is anyone except ourselves at the resort.
The other villa is located at the opposite side, by the 6000 wing and has no shielding by bamboo or other vegatation. It also backs up to the adjacent club pool. On certain days there are a lot more people and children nearby, so you are much nearer to other resort guests.
Again, I would be very happy with either villa, but would prefer the 2136 one if given a choice.