grayness vs greyness

grayness and greyness both are nouns.

Word	Noun	Adjective	Verb	Adverb
grayness	Yes	No	No	No
greyness	Yes	No	No	No

As nouns, grayness and greyness are synonyms defined as:

grayness and greyness: a neutral achromatic color midway between white and black

Other synonyms of grayness include gray, grey.

grayness (noun)	greyness (noun)
a neutral achromatic color midway between white and black	a neutral achromatic color midway between white and black