apocalypse vs cataclysm

apocalypse and cataclysm both are nouns.

Word	Noun	Adjective	Verb	Adverb
apocalypse	Yes	No	No	No
cataclysm	Yes	No	No	No

As nouns, cataclysm is a hypernym of apocalypse; that is, cataclysm is a word with a broader meaning than apocalypse:

apocalypse: a cosmic cataclysm in which God destroys the ruling powers of evil
cataclysm: an event resulting in great loss and misfortune

Other hypernyms of apocalypse include calamity, catastrophe, disaster, tragedy.

apocalypse (noun)	cataclysm (noun)
a cosmic cataclysm in which God destroys the ruling powers of evil	an event resulting in great loss and misfortune
	a sudden violent change in the earth's surface