bone black vs bone char

bone black and bone char both are nouns.

Word	Noun	Adjective	Verb	Adverb
bone black	Yes	No	No	No
bone char	Yes	No	No	No

As nouns, bone black and bone char are synonyms defined as:

bone black and bone char: black substance containing char in the form of carbonized bone; used as a black pigment

Other synonyms of bone black include animal black, animal charcoal.

bone black (noun)	bone char (noun)
black substance containing char in the form of carbonized bone; used as a black pigment	black substance containing char in the form of carbonized bone; used as a black pigment