field bean vs shell bean plant

field bean and shell bean plant both are nouns.

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

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

field bean: Old World upright plant grown especially for its large flat edible seeds but also as fodder
shell bean plant: a bean plant grown primarily for its edible seed rather than its pod

Other hypernyms of field bean include shell bean.

field bean (noun)	shell bean plant (noun)
Old World upright plant grown especially for its large flat edible seeds but also as fodder	a bean plant grown primarily for its edible seed rather than its pod