hoya vs Hoya carnosa

hoya and Hoya carnosa both are nouns.

Word	Noun	Adjective	Verb	Adverb
hoya	Yes	No	No	No
Hoya carnosa	Yes	No	No	No

As nouns, Hoya carnosa is a hyponym of hoya; that is, Hoya carnosa is a word with a more specific, narrower meaning than hoya:

hoya: any plant of the genus Hoya having fleshy leaves and usually nectariferous flowers
Hoya carnosa: succulent climber of southern Asia with umbels of pink and white star-shaped flowers

Other hyponyms of hoya include honey plant, wax plant.

hoya (noun)	Hoya carnosa (noun)
any plant of the genus Hoya having fleshy leaves and usually nectariferous flowers	succulent climber of southern Asia with umbels of pink and white star-shaped flowers