What's the difference between compilation debug="false" and Release mode?

Here's the best explanation that I found:

http://odetocode.com/blogs/scott/archive/2005/11/15/debug-and-release-builds-in-asp-net-2-0.aspx

ScottGu did a pretty good right up of the differences here on his blog.

I typically use this mode when I need to do debugging inside of Visual Studio or if I'm trying to track down a particularly nasty bug. So I usually run with debug mode to set to false.