Ubuntu is often pushed as a free product. True, you can write to Canonical and get a CD mailed to you (I got one but it was of no use) without paying a cent. You can download Ubuntu free (you can do this with most, if not all, GNU/Linux distributions though in some cases you get a "lite" version; the full version is available to paying customers) and you can continue to update the same version for 18 months. But Canonical offers paid support contracts as well.

Ubuntu comes of good stock - it is based on the unstable branch of the Debian GNU/Linux distribution. (Debian has three branches of development - stable, testing and unstable - at any one time. Stable is just that, rock-solid stable; testing is the branch that becomes the next release and unstable is bleeding edge and meant for experienced users). Debian's one problem has been lack of a release schedule - as it is a community project, releases are made when the software is ready. Ubuntu has changed that - every six months, ready or not, there is a release. Some releases have more serious bugs than others.

But Ubuntu also differs from Debian in many ways, to the extent that many senior Debian developers have accused the project of deviating too far from Debian's releases. While many Debian packages work with Ubuntu, others are ported to the latter by changing compile-time options and also the manner of specifying dependencies.

Ubuntu distributes proprietary drivers for video cards and other hardware as part of its main distribution; these come as pre-built and linked kernel modules. Debian does not include proprietary drivers as defaults; users can choose them if they so wish. And while Ubuntu's stated goal is to provide both the server and the desktop user with a distribution which is highly polished and meant to be used by non-techie types, Debian's goal is to put out a general purpose distribution which consists entirely of free software.

There has been plenty of friction between the Ubuntu and Debian projects with the name-calling growing in intensity recently. Basically, the Debian folk think that Ubuntu takes a lot from their project and gives very little back. Things reached such a stage last year that some Debian developers turned up at a conference wearing T-shirts which said "F... Ubuntu."