We offer fireclay kitchen sinks, basins and vitreous china pedestal basins. The answer, as far as the surface glaze you see, is that there’s not much of a difference at all. All of these materials are substances formed by firing clay and other minerals at high temperature.
The BEST technical definitions are :
Fireclay China : Mixture of clay and minerals, similar to vitreous china, which is molded, glazed and fired at intense temperatures. Due to the dry nature of clay mixture, can expand under various temperatures, absorbing moisture thus causing spider web like crack-lines to form sometimes which is natural and add to the beauty of the look.
Vitreous China : Mixture of clay, feldspar and quartz which is molded, glazed and “baked” at extremely high temperatures, resulting in a material which is strong, nonporous and impervious to absorption. Term refers to both the basic fixture material and the surface glaze used in the manufacture of such plumbing fixtures as lavatories, toilets and bidets. Due to the higher manufacturing cost and wastage at the production line often results in a higher retail pricing.