cave in vs collapse

cave in and collapse both are nouns.

Word	Noun	Adjective	Verb	Adverb
cave in	Yes	No	Yes	No
collapse	Yes	No	Yes	No

As nouns, collapse is a hypernym of cave in; that is, collapse is a word with a broader meaning than cave in:

cave in: the sudden collapse of something into a hollow beneath it
collapse: a natural event caused by something suddenly falling down or caving in

As verbs, cave in and collapse are synonyms defined as:

Other synonyms of cave in include break, fall in, founder, give, give way.

cave in (noun)	collapse (noun)
the sudden collapse of something into a hollow beneath it	the act of throwing yourself down; collapse; sink
	a natural event caused by something suddenly falling down or caving in
	a sudden large decline of business or the prices of stocks (especially one that causes additional failures)
	an abrupt failure of function or complete physical exhaustion

cave in (verb)	collapse (verb)
break down, literally or metaphorically	collapse due to fatigue, an illness, or a sudden attack
	lose significance, effectiveness, or value
	suffer a nervous breakdown
	break down, literally or metaphorically
	fold or close up
	fall apart
	cause to burst