downy ash vs ash tree

downy ash and ash tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
downy ash	Yes	No	No	No
ash tree	Yes	No	No	No

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

downy ash: smallish American tree with velvety branchlets and lower leaf surfaces
ash tree: any of various deciduous pinnate-leaved ornamental or timber trees of the genus Fraxinus

Other hypernyms of downy ash include ash.

downy ash (noun)	ash tree (noun)
smallish American tree with velvety branchlets and lower leaf surfaces	any of various deciduous pinnate-leaved ornamental or timber trees of the genus Fraxinus