china clay vs kaolin

china clay and kaolin both are nouns.

Word	Noun	Adjective	Verb	Adverb
china clay	Yes	No	No	No
kaolin	Yes	No	No	No

As nouns, china clay and kaolin are synonyms defined as:

china clay and kaolin: a fine usually white clay formed by the weathering of aluminous minerals (as feldspar); used in ceramics and as an absorbent and as a filler (e.g., in paper)

Other synonyms of china clay include china stone, kaoline, porcelain clay, terra alba.

china clay (noun)	kaolin (noun)
a fine usually white clay formed by the weathering of aluminous minerals (as feldspar); used in ceramics and as an absorbent and as a filler (e.g., in paper)	a fine usually white clay formed by the weathering of aluminous minerals (as feldspar); used in ceramics and as an absorbent and as a filler (e.g., in paper)