I wonder what the real difference between these two services, made for Ubuntu.
Ask Ubuntu (this website) is a member of the StackExchange network. Although it has the support of the Ubuntu community, it is not affiliated with Canonical Ltd. This site is designed to make it easy to get answers to specific questions about using Ubuntu. This site was launched in July of 2010.
The Ubuntu forums on the other hand are officially run by Canonical Ltd. and have a slightly broader scope than this site. Questions there are structured more around discussion rather than the question / answer format that Ask Ubuntu uses. The Ubuntu forums have been around since 2004.
Ubuntu is a computer operating system based on the Debian Linux distribution and distributed as free and open source software. It is named after the Southern African philosophy of Ubuntu ("humanity towards others"). (copied from wikipedia/Ubuntu 2011-05-09 18:46 UTC)
Ubuntu is designed primarily for desktop use, although netbook and server editions exist as well. Web statistics suggest that Ubuntu's share of Linux desktop usage is about 50%, and indicate upward-trending usage as a web server. Ubuntu holds an estimated global usage of more than 12 million users. (copied from wikipedia/Ubuntu 2011-05-09 18:46 UTC)
Ask Ubuntu is a community driven Question and Answer website for the Ubuntu Linux operating system. It is part of the Stack Exchange Network, running the same software as Stack Overflow. Ask Ubuntu started life as a "Proposed Q&A site for ubuntu users and developers" on Stack Exchange. With other internet users supporting the proposal through "commitment" Stack Exchange chose to launch the site in a beta form. (copied from wikipedia/Ask_Ubuntu 2011-05-09 18:46 UTC)