oxford grey vs oxford gray

oxford grey and oxford gray both are nouns.

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

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

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

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