smash-up vs collision

smash-up and collision both are nouns.

Word	Noun	Adjective	Verb	Adverb
smash-up	Yes	No	No	No
collision	Yes	No	No	No

As nouns, collision is a hypernym of smash-up; that is, collision is a word with a broader meaning than smash-up:

smash-up (noun)	collision (noun)
a serious collision (especially of motor vehicles)	a conflict of opposed ideas or attitudes or goals
	an accident resulting from violent impact of a moving object
	(physics) a brief event in which two or more bodies come together