IME, they are very close to the same size and have the same number of splines. like i say, it involves some finesse and a bit of good judgment as to how hard to go at it. eventually the splines have worn a bit and now will engage to about a milimeter or so on any cassette lockring i've found, which is what i need. i've even, by chance, bought an after market cassette lockring that the freewheel tool fits into without encouragement.

one needs to be bold and pretty much care not a whit about the lockring. i've found them to be plenty tough. at least the steel ones.

but i am more than willing to accept that others may not find this something that they are comfortable with. i wasn't at first, but now, i just pound it in a twist.