Center of Area

 (aka: center of pressure)

In the case of a flat sheet of paper or cardboard, the center of mass and the center of area are located at the same point. If a weight is taped onto the surface of the cardboard at some random location, the center of area remains unaffected, but the center of mass moves toward the added weight. Because the area and outline of the shape were unaffected, but the mass distribution changed, the center of mass and the center of area are no longer located at the same place.

Comparing the center of area and the center of mass.