One big difference (and it seems many people have troubles with it) is IDEA's handling of library projects. Unfortunately I think this is done in a very logical way, as each "project" is handled as a model. Means you create a project ("My app"), add a module for your main app project, and add new modules for each library project you would add. For each modules you can set the dependencies and say on which modules it depends.
In the newest version (12) Jetbrains also added an Android UI designer, which was one of the features not available before.
If you are curious you can download and install IDEA from their website, or when you are using Ubuntu you can simply download it from Software center.
And here's a nice article given a quick introduction: