Rolling bearing includes ball and roller bearings. The two basic types of rolling element distinguish the two basic types of rolling bearing:
Balls and rollers are different in how they make contact with the raceways. Balls make point contact with the ring raceways. With increasing load acting on the bearing, the contact point becomes an elliptical area. The small contact area provides low rolling friction, which enables ball bearings to accommodate high speeds but also limits their load-carrying capacity.
Rollers make line contact with the ring raceways. With increasing load acting on the bearing, the contact line becomes somewhat rectangular in shape. Because of the larger contact area and the consequently higher friction, a roller bearing can accommodate heavier loads, but lower speeds, than a same-sized ball bearing.
if you classified rolling bearings with the direction of the load, the rolling bearings can be classified into two groups of bearings:
Radial bearings accommodate loads that are predominantly perpendicular to the shaft. Some radial bearings can support only pure radial loads, while most can additionally accommodate some axial loads in one direction and, in some cases, both directions.
Thrust bearings accommodate loads that act predominantly along the axis of the shaft. Depending on their design, thrust bearings may support pure axial loads in one or both directions, nd some can additionally accommodate radial loads (combined loads). Thrust bearings cannot accommodate speeds as high as same-sized radial bearings.