epiphyllum vs cactus

epiphyllum and cactus both are nouns.

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

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

epiphyllum: any cactus of the genus Epiphyllum having flattened jointed irregularly branching stems and showy tubular flowers
cactus: any succulent plant of the family Cactaceae native chiefly to arid regions of the New World and usually having spines

epiphyllum (noun)	cactus (noun)
any cactus of the genus Epiphyllum having flattened jointed irregularly branching stems and showy tubular flowers	any succulent plant of the family Cactaceae native chiefly to arid regions of the New World and usually having spines