olive-gray vs olive-grey

olive-gray and olive-grey both are adjectives.

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

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

olive-gray (adjective)	olive-grey (adjective)
of grey tinged with olive	of grey tinged with olive