The main difference is the amount of inputs... as with most mixers, the model number represents the in's/buses, so for example the 1202 has 12 in's and 2 buses. If you don't have any external preamps, only the 1202 comes with 4, so only that one will be able to handle 4 mic inputs (the other 2 you listed have 2 pre's)
Hope this helps!
The difference is the amount of channels it has and how many it can record simultaniously. I'm not very familiar with Behringer products, but I think they all can only record 2 simultanious channels. Remember it this way, UB (Ultra Behringer) 8 (amount of channels) 02 (amount of simultanious channels).
any of those mixers will work ---just remember behringer has a bad habit of putting several stereo channels on each board and including them in the channel number figures --IE: 8002 has 4 XLR inputs, 2 stereo inputs makes for 4 inputs, 2 outputs, maybe 2 inserts on up the chain.......