Korean velvet grass vs zoysia

Korean velvet grass and zoysia both are nouns.

Word	Noun	Adjective	Verb	Adverb
Korean velvet grass	Yes	No	No	No
zoysia	Yes	No	No	No

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

Korean velvet grass: Asiatic creeping perennial grass; introduced in southern United States as a drought-resistant lawn grass
zoysia: any of several creeping grasses of the genus Zoysia

Korean velvet grass (noun)	zoysia (noun)
Asiatic creeping perennial grass; introduced in southern United States as a drought-resistant lawn grass	any of several creeping grasses of the genus Zoysia