japanese clover vs japan clover

japanese clover and japan clover both are nouns.

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

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

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

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

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