No aside from not-being equal they have different specs too,8800GT has 112 StreamProcessors whereas 8800GTS 512 has 128
oh I see I see, thanks for the reply
The two cores are the same except one cluster is disabled but either than that the primary reason why SLI with these wont work is due to the driver. The two cards must have the same ID chain in order to work. Nvidia did this to prevent people from putting one cheap card in sli with one mid range or high part while still getting a FPS increase. Again sli can only work with cards that have the same core.