dark-grey vs dark-gray

dark-grey and dark-gray both are adjectives.

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

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

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

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