Ubuntu and Fedora are arguably the most popular Linux distros out there today. They both make a huge impact on the Linux community release after release, but are somewhat opposite philosphies at times. Fedora, the RedHat-sponsored community project is adamant of RPM packages, while Ubuntu is based on Debian and therefore uses DEB packages. Fedora maintains that RedHat corporate environment vibe to it, more like a specialised distro, the perfect choice for developers. Ubuntu, on the other hand, based its strategy around creating "Linux for human beings", a friendly desktop environment that is accessible to all kinds of users.

Read the full thing at http://cristalinux.blogspot.com/2011/05/how-to-painlessly-switch-from-ubuntu-to.html