japan clover vs lespedeza

japan clover and lespedeza both are nouns.

Word	Noun	Adjective	Verb	Adverb
japan clover	Yes	No	No	No
lespedeza	Yes	No	No	No

As nouns, lespedeza is a hypernym of japan clover; that is, lespedeza is a word with a broader meaning than japan clover:

japan clover: an annual of tropical Asia naturalized in United States
lespedeza: shrubby or herbaceous plants widely used for forage, soil improvement, and especially hay in southern United States

Other hypernyms of japan clover include bush clover.

japan clover (noun)	lespedeza (noun)
an annual of tropical Asia naturalized in United States	shrubby or herbaceous plants widely used for forage, soil improvement, and especially hay in southern United States