collision vs impinging

collision and impinging both are nouns.

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

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

collision: (physics) a brief event in which two or more bodies come together
impinging: the physical coming together of two or more things

Other hypernyms of collision include contact, striking.

collision (noun)	impinging (noun)
a conflict of opposed ideas or attitudes or goals	the physical coming together of two or more things
an accident resulting from violent impact of a moving object
(physics) a brief event in which two or more bodies come together