As I can tell you are all ready an UB player..
Absolute is the same thing except maybe a better table layout?
It's good to have both of them if your a freeroller because different private freerolls for different days in both..not really much different
Absolute Bet is the same like the Ultimate bet site, a good site but its very hard when you want a withdran :s unfortunetely. And too many good players play in there