What is the difference between center of mass and centroid?

Let say you have a pie with one half full of iron and the other half full of cranberries.

The geometric centroid will be the center of the circle since it is the middle of the geometric form

The center of mass is the exact point where you need to put your finger to hold in equilibrium the plate. It will necessarily be on the iron stuffed side since iron is heavier than cranberries thus moving the center of mass towards iron.