Single-direction thrust ball bearing is made by axial ring, washer, ball and retainer. It only bear axial load, it can not bear any radial load. It allowed orientation to axes unidirectional.
Double-direction thrust ball bearing is separable bearing. It is made by double -face groove axial ring, two washers, two balls and retainer. It may bear bidirectional axial load. It can not bear any radial load. It allowed orientation to axes bidirectional.