china vs bone china

china and bone china both are nouns.

Word	Noun	Adjective	Verb	Adverb
china	Yes	No	No	No
bone china	Yes	No	No	No

As nouns, bone china is a hyponym of china; that is, bone china is a word with a more specific, narrower meaning than china:

Other hyponyms of china include crackle, crackle china, crackleware.

china (noun)	bone china (noun)
high quality porcelain originally made only in China	fine porcelain that contains bone ash
dishware made of high quality porcelain