recoil vs occur

recoil is a noun but occur is not a noun.

Word	Noun	Adjective	Verb	Adverb
recoil	Yes	No	Yes	No
occur	No	No	Yes	No

As verbs, occur is a hypernym of recoil; that is, occur is a word with a broader meaning than recoil:

Other hypernyms of recoil include come about, fall out, go on, hap, happen, pass, pass off, take place.

recoil (noun)	occur (noun)
a movement back from an impact
the backward jerk of a gun when it is fired

recoil (verb)	occur (verb)
spring back, as from a forceful thrust	come to pass
draw back, as with fear or pain	come to one's mind; suggest itself
spring back; spring away from an impact	to be found to exist
come back to the originator of an action with an undesired effect