repeat vs occur

repeat is a noun but occur is not a noun.

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

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

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

repeat (noun)	occur (noun)
an event that repeats

repeat (verb)	occur (verb)
happen or occur again	come to pass
to say, state, or perform again	come to one's mind; suggest itself
to say again or imitate	to be found to exist
make or do or perform again
repeat an earlier theme of a composition
do over