charcoal vs charcoal-gray

charcoal is a noun but charcoal-gray is not a noun.

Word	Noun	Adjective	Verb	Adverb
charcoal	Yes	Yes	Yes	No
charcoal-gray	No	Yes	No	No

As adjectives, charcoal and charcoal-gray are synonyms defined as:

Other synonyms of charcoal include charcoal-grey.

charcoal (noun)	charcoal-gray (noun)
a stick of black carbon material used for drawing
a drawing made with a stick of black carbon material
a very dark grey color
a carbonaceous material obtained by heating wood or other organic matter in the absence of air

charcoal (adjective)	charcoal-gray (adjective)
of a very dark grey	of a very dark grey

charcoal (verb)	charcoal-gray (verb)
draw, trace, or represent with charcoal