Debian is primarily aimed at servers and stability. All the desktop apps are 2 or so years old in the stable branch. Ubuntu takes Debian and changes it to be desktop orientated with much more up to date desktop programs. Likely with a minor bit of sacrifice to the server side of things.
Uhh thats a prejudice. In testing and unstable (often more stable than other distros
) have always been new versions. Releasing new stable versions took much time, but it's now better.
Just a bit of *cough* light exaggeration perhaps. It's been a couple of years since I switched to ubuntu. If anything a 6 month release cycle makes ubuntu SEEM faster. At least I mentioned stable.