Prunus insititia vs plum tree

Prunus insititia and plum tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
Prunus insititia	Yes	No	No	No
plum tree	Yes	No	No	No

As nouns, plum tree is a hypernym of Prunus insititia; that is, plum tree is a word with a broader meaning than Prunus insititia:

Prunus insititia: small wild or half-domesticated Eurasian plum bearing small ovoid fruit in clusters
plum tree: any of several trees producing edible oval fruit having a smooth skin and a single hard stone

Other hypernyms of Prunus insititia include plum.

Prunus insititia (noun)	plum tree (noun)
small wild or half-domesticated Eurasian plum bearing small ovoid fruit in clusters	any of several trees producing edible oval fruit having a smooth skin and a single hard stone