Prunus padus vs bird cherry

Prunus padus and bird cherry both are nouns.

Word	Noun	Adjective	Verb	Adverb
Prunus padus	Yes	No	No	No
bird cherry	Yes	No	No	No

As nouns, bird cherry is a hypernym of Prunus padus; that is, bird cherry is a word with a broader meaning than Prunus padus:

Prunus padus: small European cherry tree closely resembling the American chokecherry
bird cherry: any of several small-fruited cherry trees frequented or fed on by birds

Other hypernyms of Prunus padus include bird cherry tree.

Prunus padus (noun)	bird cherry (noun)
small European cherry tree closely resembling the American chokecherry	any of several small-fruited cherry trees frequented or fed on by birds