beach plum vs beach plum bush

beach plum and beach plum bush both are nouns.

Word	Noun	Adjective	Verb	Adverb
beach plum	Yes	No	No	No
beach plum bush	Yes	No	No	No

As nouns, beach plum and beach plum bush are synonyms defined as:

beach plum and beach plum bush: seacoast shrub of northeastern North America having showy white blossoms and edible purple fruit

Other synonyms of beach plum include Prunus maritima.

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