pitahaya cactus vs cactus

pitahaya cactus and cactus both are nouns.

Word	Noun	Adjective	Verb	Adverb
pitahaya cactus	Yes	No	No	No
cactus	Yes	No	No	No

As nouns, cactus is a hypernym of pitahaya cactus; that is, cactus is a word with a broader meaning than pitahaya cactus:

pitahaya cactus: cactus of the southwestern United States and northern Mexico having edible juicy fruit
cactus: any succulent plant of the family Cactaceae native chiefly to arid regions of the New World and usually having spines

pitahaya cactus (noun)	cactus (noun)
cactus of the southwestern United States and northern Mexico having edible juicy fruit	any succulent plant of the family Cactaceae native chiefly to arid regions of the New World and usually having spines