I really don't know the difference. I might some day care, but today I don't. Model M keyboards that are excessively ping-y or clacky, I really don't know. I'm usually pretty observant about this sort of thing but when a keyboard is as loud and obtrusive as a Model M my senses tend to dull the subtle differences among the various makes and vintages of that keyboard.
I'm probably going to need a Unicomp SpaceSaver before this obsession runs its course, too.