oxford grey vs charcoal grey

oxford grey and charcoal grey both are nouns.

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

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

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

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