japan clover vs japanese clover

japan clover and japanese clover both are nouns.

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

As nouns, japan clover and japanese clover are synonyms defined as:

japan clover and japanese clover: an annual of tropical Asia naturalized in United States

Other synonyms of japan clover include jap clover, Lespedeza striata.

japan clover (noun)	japanese clover (noun)
an annual of tropical Asia naturalized in United States	an annual of tropical Asia naturalized in United States