A roller bearing is a type of rolling-element bearing that uses cylindrical or barrel-shaped rolling elements (called rollers) to carry a load while minimizing friction.

The ball bearing is a type of bearing that contains a ball to maintain the clearance between the bearing races. The motion of the ball reduces the friction compared to flat surfaces sliding against each other. 

Tapered roller bearings are designed to handle combination loads, such as both axial and radial loads acting simultaneously. they provide low friction during operation and have a long service life.