unavoidable casualty vs act of God

unavoidable casualty and act of God both are nouns.

Word	Noun	Adjective	Verb	Adverb
unavoidable casualty	Yes	No	No	No
act of God	Yes	No	No	No

As nouns, unavoidable casualty and act of God are synonyms defined as:

unavoidable casualty and act of God: a natural and unavoidable catastrophe that interrupts the expected course of events

Other synonyms of unavoidable casualty include force majeure, inevitable accident, vis major.

unavoidable casualty (noun)	act of God (noun)
a natural and unavoidable catastrophe that interrupts the expected course of events	a natural and unavoidable catastrophe that interrupts the expected course of events