beach plum vs wild plum tree

beach plum and wild plum tree both are nouns.

Word	Noun	Adjective	Verb	Adverb
beach plum	Yes	No	No	No
wild plum tree	Yes	No	No	No

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

beach plum: seacoast shrub of northeastern North America having showy white blossoms and edible purple fruit
wild plum tree: an uncultivated plum tree or shrub

Other hypernyms of beach plum include wild plum.

beach plum (noun)	wild plum tree (noun)
small dark purple fruit used especially in jams and pies	an uncultivated plum tree or shrub
seacoast shrub of northeastern North America having showy white blossoms and edible purple fruit