fava bean vs field bean

fava bean and field bean both are nouns.

Word	Noun	Adjective	Verb	Adverb
fava bean	Yes	No	No	No
field bean	Yes	No	No	No

fava bean (noun)	field bean (noun)
shell beans cooked as lima beans	Old World upright plant grown especially for its large flat edible seeds but also as fodder
seed of the broad-bean plant