blue-gray vs bluish-grey

blue-gray and bluish-grey both are adjectives.

Word	Noun	Adjective	Verb	Adverb
blue-gray	No	Yes	No	No
bluish-grey	No	Yes	No	No

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

Other synonyms of blue-gray include blue-grey, bluish-gray.

blue-gray (adjective)	bluish-grey (adjective)
of grey tinged with blue	of grey tinged with blue