Vicia faba vs shell bean

Vicia faba and shell bean both are nouns.

Word	Noun	Adjective	Verb	Adverb
Vicia faba	Yes	No	No	No
shell bean	Yes	No	No	No

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

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

Other hypernyms of Vicia faba include shell bean plant.

Vicia faba (noun)	shell bean (noun)
Old World upright plant grown especially for its large flat edible seeds but also as fodder	unripe beans removed from the pod before cooking
	a bean plant grown primarily for its edible seed rather than its pod