shell bean vs bean plant

shell bean and bean plant both are nouns.

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

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

shell bean: a bean plant grown primarily for its edible seed rather than its pod
bean plant: any of various leguminous plants grown for their edible seeds and pods

Other hypernyms of shell bean include bean.

shell bean (noun)	bean plant (noun)
unripe beans removed from the pod before cooking	any of various leguminous plants grown for their edible seeds and pods
a bean plant grown primarily for its edible seed rather than its pod