Davy's gray vs steel grey

Davy's gray and steel grey both are nouns.

Word	Noun	Adjective	Verb	Adverb
Davy's gray	Yes	No	No	No
steel grey	Yes	No	No	No

As nouns, Davy's gray and steel grey are synonyms defined as:

Other synonyms of Davy's gray include Davy's grey, iron blue, steel gray.

Davy's gray (noun)	steel grey (noun)
slightly purplish or bluish dark grey	slightly purplish or bluish dark grey