checkpoint column defender

On the "Review changes to your computer settings" page of Windows Explorer, there are columns titled Agent and Checkpoint. The Agent contains entries like "Auto Start" and "Services and Drivers". The Checkpoint column contains entries like "Run Keys", "Drivers", and Services. Anyone know what these are about, specifically. For example, I assume Services has something to do with the Services snap-in. Drivers just refers to the fact that the item is a driver. But what's up with Auto Start (it doesn't seem to correspond to an entry in the Startup folder). And I'm really not sure that Checkpoint and Run Keys are about at all.