What is the difference between this site, Ask Ubuntu, and Ask Ubuntu Meta?
The FAQ does a great job explaining the differences:
What kind of questions can I ask here?
- Are questions about _ on or off topic?
- What should our FAQ contain?
- How should we tag questions about _?
- What should our elevator pitch be?
- What should our site design look like?
- Who should the moderators be?
- How do we promote our site?
AskUbuntu Meta is a site where questions (such as this one) should be posted to ask about AskUbuntu itself.
From the about page:
The FAQ explicitly disallows meta-discussion on the main site, to reduce clutter and noise. This frustrated many members of the community who wanted to ask questions about how and why the website works the way it does. We needed an outlet for this activity, a separate place where community members could go for sanctioned meta-discussion. And here it is!
The focus of this site is the content topic. If the question is about the Stack Exchange engine in a general sense, it should be asked on Meta Stack Overflow instead.
Here is the FAQ page where you can learn more.