All that I've noticed is the look and feel, I haven't really seen much of a usability difference, but I don't use linux all that often so someone with more experience with it may be able to offer more help. I generally just use whichever I feel like using at the time. I can't seem to really choose one over the other permenantly, although I prefer KDE only a little more then Gnome.
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"Fuck these chains
No goddamn slave
I will be different" ~ Machine Head
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