charcoal grey vs oxford gray

charcoal grey and oxford gray both are nouns.

Word	Noun	Adjective	Verb	Adverb
charcoal grey	Yes	No	No	No
oxford gray	Yes	No	No	No

As nouns, charcoal grey and oxford gray are synonyms defined as:

Other synonyms of charcoal grey include charcoal, charcoal gray, oxford grey.

charcoal grey (noun)	oxford gray (noun)
a very dark grey color	a very dark grey color