Why is it that you are asking? It should be as simple as ordering what you need 8 way, 4 way, * way...
But in case you're wondering the difference between an 8 and 4 way is that an 8 way allows two microswitches to be operated at the same time and therefore register that as a diagonal. 4 ways usually have some sort of restrictor that only allows the joystick's shaft to contact 1 microswitch at a time.