reddish-gray vs red-grey

reddish-gray and red-grey both are adjectives.

Word	Noun	Adjective	Verb	Adverb
reddish-gray	No	Yes	No	No
red-grey	No	Yes	No	No

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

Other synonyms of reddish-gray include red-gray, reddish-grey.

reddish-gray (adjective)	red-grey (adjective)
of grey tinged with red	of grey tinged with red