User level stuff is the same - but if you're talking about system
administration, then yes, suse/sles yast is different from what's in
debian/ubuntu, which is different from the redhat/fedora stuff, but
under the hood the same things are ultimately happening.

Trust me, Joe Six-pack and Aunt Mildred are never going to "integrate
new sound drivers into kernel" - anyone doing that sort of thing
wouldn't depend on a GUI anyway

As far as adding new hardware - I'm not sure how a GUI enters into that
either. In my experience Linux detects the new hardware and works, or
prompts you. Do you have a specific example?