Very simple.
A constant running
PTO or live
PTO is the best. It allows you to stop the tractor without stopping what ever you have attached to the
PTO.
A
PTO if not constant running will both stop the tractor and implement when you stop the tractor. Also the inertisa from the implement, such as a bush hog, will push your tractor because it works directly off the transmission. A internal over run clutch allows the implement you have attached to the
PTO to still turn while it is stopping but not push the tractor.
This is a very simple explaniation but I hope it helps.
If you can afford it buy a tractor with a constant running
PTO.
Don