Ubuntu vs Xubuntu
Ubuntu is the most widely-used Linux distribution. Xubuntu is an Ubuntu-based distribution which provides the Xfce desktop environment instead of the Gnome environment. It is designed for old or low-end computers. Xubuntu is also suitable for users who want quicker performance on their computer, those who prefer to have more control over their configuration (Xubuntu comes with a lot less enabled out of the box), and users who prefer the Xfce environment.
 Fit and Finish
Both provide a high level of "fit and finish" in a linux distribution - easy to configure, and set up "out-of-the-box" to work on a wide variety of hardware, and to meet a wide variety of users' needs. Both come with feature-rich programs for word processing, spreadsheets, and web browsing. The programs are compatible with Microsoft programs for the same purposes.
 Preinstalled Software
Xubuntu does not come preinstalled with a presentation program, while Ubuntu does (OpenOffice Impress). Ubuntu also comes with a video editor (PiTiVi) and music library manager (Rhythmbox). All of these programs can be installed in Xubuntu.