oxford-gray vs dark-grey

oxford-gray and dark-grey both are adjectives.

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

As adjectives, oxford-gray and dark-grey are synonyms defined as:

Other synonyms of oxford-gray include dark-gray, oxford-grey.

oxford-gray (adjective)	dark-grey (adjective)
of a dark shade of grey	of a dark shade of grey