field bean vs fava bean

field bean and fava bean both are nouns.

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

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