green ash vs red ash

green ash and red ash both are nouns.

Word	Noun	Adjective	Verb	Adverb
green ash	Yes	No	No	No
red ash	Yes	No	No	No

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

green ash: a variety of red ash having glossy branchlets and lower leaf surfaces
red ash: smallish American tree with velvety branchlets and lower leaf surfaces

Other hypernyms of green ash include downy ash, Fraxinus pennsylvanica.

green ash (noun)	red ash (noun)
a variety of red ash having glossy branchlets and lower leaf surfaces	smallish American tree with velvety branchlets and lower leaf surfaces