For me the difference is best illustrated by the following.
KDE provides me with a file browser with a selection of default values selected, but with the option to change most of them according to my particular preference.
Gnome provides me with a file browser from which they're removed most options and over which I'm then insulted when I ask "what sort of design team removes options, particularly when half their user base is screaming at them not do so?" If I wanted a dumb media consumption device I'd have bought an Apple Mac. I am extremely cautious of the "don't try to think, let us do it for you' approach to UI design. It never works.