Total noob question about mc origin point

This is something I’ve wondered about and been meaning to ask for a long time: there are two icons that become visible when a mc is selected, a small crosshair and a small circle. Sometimes they’re in the same place, sometimes not. I understand the small crosshair is the origin, where all transforms originate from, but what’s the circle, and what does it mean when the two icons are in different locations?

Thanks!