pumpkin ash vs ash tree

pumpkin ash and ash tree both are nouns.

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

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

pumpkin ash: timber tree of central and southeastern United States having hairy branchlets and a swollen trunk base
ash tree: any of various deciduous pinnate-leaved ornamental or timber trees of the genus Fraxinus

Other hypernyms of pumpkin ash include ash.

pumpkin ash (noun)	ash tree (noun)
timber tree of central and southeastern United States having hairy branchlets and a swollen trunk base	any of various deciduous pinnate-leaved ornamental or timber trees of the genus Fraxinus