slaty-gray vs slaty-grey

slaty-gray and slaty-grey both are adjectives.

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

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

Other synonyms of slaty-gray include slate-gray, slate-grey, slatey, slaty, stone-gray, stone-grey.

slaty-gray (adjective)	slaty-grey (adjective)
of the color of slate or granite	of the color of slate or granite