Japanese carpet grass vs zoysia

Japanese carpet grass and zoysia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Japanese carpet grass	Yes	No	No	No
zoysia	Yes	No	No	No

As nouns, zoysia is a hypernym of Japanese carpet grass; that is, zoysia is a word with a broader meaning than Japanese carpet grass:

Japanese carpet grass: lawn grass common in the Philippines; grown also in United States
zoysia: any of several creeping grasses of the genus Zoysia

Japanese carpet grass (noun)	zoysia (noun)
lawn grass common in the Philippines; grown also in United States	any of several creeping grasses of the genus Zoysia