sieva bean vs shell bean plant

sieva bean and shell bean plant both are nouns.

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

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

sieva bean: bush bean plant cultivated especially in southern United States having small flat edible seeds
shell bean plant: a bean plant grown primarily for its edible seed rather than its pod

Other hypernyms of sieva bean include shell bean.

sieva bean (noun)	shell bean plant (noun)
small flat green bean similar to lima beans	a bean plant grown primarily for its edible seed rather than its pod
bush bean plant cultivated especially in southern United States having small flat edible seeds