No NT4 is of the same lineage as 2000. I was referring to the other lineage of Windows with ME being the last one. The unification that XP provided was good for stability, but the eventual result is this whole Windows 11 ordeal.

I meant the UI; NT4 and 2000 were the nice and clean ones, for enterprise and professionals; ME had already first signs of the cartoon world, that XP continued on.

Looking back at the comment, yes, you are right. Both lines could share under the hood stuff, the NT/2000 line with clean UI and the ME line the colorized cartoon one. Or, they could split the line with Home and Pro, both of them they still have.