oxford gray vs charcoal grey

oxford gray and charcoal grey both are nouns.

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

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

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

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