slaty-grey vs slaty-gray

slaty-grey and slaty-gray both are adjectives.

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

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

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

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