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.