bush bean vs bean plant

bush bean and bean plant both are nouns.

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

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

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

Other hypernyms of bush bean include bean.

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