bush bean vs bean

bush bean and bean both are nouns.

Word	Noun	Adjective	Verb	Adverb
bush bean	Yes	No	No	No
bean	Yes	No	Yes	No

As nouns, bean is a hypernym of bush bean; that is, bean is a word with a broader meaning than bush bean:

bush bean: a bean plant whose bushy growth needs no supports
bean: any of various leguminous plants grown for their edible seeds and pods

Other hypernyms of bush bean include bean plant.

bush bean (noun)	bean (noun)
a bean plant whose bushy growth needs no supports	informal terms for a human head
	any of various edible seeds of plants of the family Leguminosae used for food
	any of various leguminous plants grown for their edible seeds and pods
	any of various seeds or fruits that are beans or resemble beans

bush bean (verb)	bean (verb)
	hit on the head, especially with a pitched baseball