iron-grey vs iron-gray

iron-grey and iron-gray both are nouns.

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

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

As nouns, iron-grey and iron-gray are synonyms defined as:

iron-grey (noun)	iron-gray (noun)
the color of freshly broken cast iron	the color of freshly broken cast iron

iron-grey (adjective)	iron-gray (adjective)
of the grey color of iron	of the grey color of iron