deep red vs redness

deep red and redness both are nouns.

Word	Noun	Adjective	Verb	Adverb
deep red	Yes	No	No	No
redness	Yes	No	No	No

As nouns, redness is a hypernym of deep red; that is, redness is a word with a broader meaning than deep red:

deep red: a deep and vivid red color
redness: red color or pigment; the chromatic color resembling the hue of blood

Other hypernyms of deep red include red.

deep red (noun)	redness (noun)
a deep and vivid red color	red color or pigment; the chromatic color resembling the hue of blood
	a response of body tissues to injury or irritation; characterized by pain and swelling and redness and heat