Full ceramic ball bearings have both ceramic balls and ceramic raceways. They can be supplied with a ball retainer, made from a non-metallic material such as PEEK or PTFE, or without a retainer (full complement). They are used in highly corrosive environments, extremes of temperature or as non-magnetic/non-conductive bearings.
Hybrid bearings, which are sometimes called ceramic bearings, are made from both steel and ceramics. Typically, the inner and outer rings are made of steel, while the balls are made from silicon nitride. Hybrids are used in high speed applications or where the bearings should be non-conductive.