Differences between a UserControl and Form

What are the differences between a UserControl and a Form?

For my application, I'm creating an application that looks like a Single Document Interface (SDI).  I have one main Form and the each button on the toolbar brings a different page to the foreground.

At the moment, each page is a child form.  What are the pro/cons of using a usercontrol for each page instead.

I've tried it and I know that I can accomplish the same look / interaction on both.

I would also like to know how each is affected by double buffering and resources.