Well, not exactly.............Yes, they all do the same thing...."ratchet"...........But there are only 2 different types that I know of.......
1........There is one that has to be installed with a roll pin that is supposed to be permanently connected to the tractor's p.t.o. shaft. What I mean by permanently is that you CAN take it off, its just more trouble to do so....I've had the roll pin break on my Forn 8N, which I sold a few years ago, but you just replace the pin.
2........The one that I like best, which is on my Yanmar YM2000, is the Quick Attach or as some say Quick Dis-Connect over-run clutch.......It can be removed and put back on on the tractor's p.t.o. shaft in a matter of 5 seconds or less.......It has the little spring-loaded "button" that you push down (like some of the brush mower pto drivelines) to get it on the shaft.............Thats why it costs more money than the one with the roll-pin........But I definitely think its worth it, myself.
Hope this helps,
Travis R