accident vs collision

accident and collision both are nouns.

Word	Noun	Adjective	Verb	Adverb
accident	Yes	No	No	No
collision	Yes	No	No	No

As nouns, collision is a hyponym of accident; that is, collision is a word with a more specific, narrower meaning than accident:

Other hyponyms of accident include crash, wreck, accidental injury, injury, shipwreck, wreck, casualty, fatal accident.

accident (noun)	collision (noun)
anything that happens suddenly or by chance without an apparent cause	a conflict of opposed ideas or attitudes or goals
an unfortunate mishap; especially one causing damage or injury	an accident resulting from violent impact of a moving object
	(physics) a brief event in which two or more bodies come together