snap bean vs green bean

snap bean and green bean both are nouns.

Word	Noun	Adjective	Verb	Adverb
snap bean	Yes	No	No	No
green bean	Yes	No	No	No

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

snap bean: tender green beans without strings that easily snap into sections
green bean: immature bean pod eaten as a vegetable

snap bean (noun)	green bean (noun)
tender green beans without strings that easily snap into sections	immature bean pod eaten as a vegetable
	seed of the mung bean plant used for food; food from the seed of the mung bean plant
	a common bean plant cultivated for its slender green edible pods
	seed of the mung bean plant; used for food; seed of the mung bean plant