Yes. They are different beasts. Each has its own different management tools,
including a different network managers. They will run on the same kernel, but
they will differ once you logon. Ubuntu will load Gnome and Kubuntu will KDE.
Each project has different developers and different goals. Kubuntu users
frequently gripe that Kubuntu gets less attention and support that Ubuntu from
its parent.
I am running Ubuntu now so can't speak for your situation. I installed Kubuntu,
but am running Gnome at the moment. I tend to go for a few weeks of one and then
switch for variety. I would say that Kubuntu is not weaker than Ubuntu just
because it does not detect your card. Generally they are quite equal to doing
tasks such as configuring networking.
If Ubuntu is working and you are happy with it, then stick with it. If you want
to try KDE, then you will have to figure out the control panel and network
manager in KDE. If you can't find the answer here, then search on
Linuxquestions.org or and in the forums of KDE specific distro such as Debian.
They will use similar tools. Fedora may also be of use here, as they have a KDE
distro. Versions that use different networking tools would be Mandriva, PCLOS,
Mint, MEPIS and OpenSUSE. They will not be able to help you since they do not
use KDE's out of the box networking tools.
One of the weaknesses of the *buntus IMO is that they do have tools of their own
and rely on Gnome or KDE's tools which are adequate, but no more. I suggest that
you download and run SimplyMEPIS 7 to compare it with Kubuntu. They have the
same heritage (Debian), but Warren Woodford has done some wondeful work to make
MEPIS more than just another KDE distro. He has added his own tools and done
much to distinguish it from the plain vanilla KDE tools. MEPIS's hardware
detection and tools are better than most. A similar distro to MEPIS is PCLOS,
also KDE, but it uses RPMs. If you can live with this and the dependency
problems then it it an excellent choice.