act of God vs cataclysm

act of God and cataclysm both are nouns.

Word	Noun	Adjective	Verb	Adverb
act of God	Yes	No	No	No
cataclysm	Yes	No	No	No

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

act of God: a natural and unavoidable catastrophe that interrupts the expected course of events
cataclysm: an event resulting in great loss and misfortune

Other hypernyms of act of God include calamity, catastrophe, disaster, tragedy.

act of God (noun)	cataclysm (noun)
a natural and unavoidable catastrophe that interrupts the expected course of events	an event resulting in great loss and misfortune
	a sudden violent change in the earth's surface