What is the difference between two sports bikes, both 600cc, but one is

Besides two cylinders, depends on which two bikes you are comparing. Engines come in many flavors, v twins, v fours, in-line 4, Parallel twin, horizontal twins ,,,etc.

The 2 cylinder bike is just a sport bike more up right position the other is a super sport which is built to race with more of a race position the 2 cylinder bike at 600ccs will go about 140mph and the super sport will go 160 - 175 depending on the bike and rider