Semantics here, but JP is balding, and JLB I reckon is too. I feel like JLB got a hair transplant, and there was a middle of the point 2000s where it looked bad. JR is both balding/bald and shaven. I haven't really looked closely at his dome to see his balding process, and he keeps his dome against the grain smooth. I'm much more lazy with my noggin.
I haven't seen the usual lighter vs darker patches where hair still grows with JR, but u haven't really looked either.
IMO, JP is getting closer to a point where he will either transplant, shorten it, or just continue and Devin Townsend it.
I honestly do not know any attributes of them, so the only things we have are physical things. Some of those are changeable in themselves- JP is clearly the most active working out, but JM does like 250 push-ups apparently before shows. JLB fell out of shape only to get in shape in 2003.