recurrent event vs occurrence

recurrent event and occurrence both are nouns.

Word	Noun	Adjective	Verb	Adverb
recurrent event	Yes	No	No	No
occurrence	Yes	No	No	No

As nouns, occurrence is a hypernym of recurrent event; that is, occurrence is a word with a broader meaning than recurrent event:

Other hypernyms of recurrent event include happening, natural event, occurrent.

recurrent event (noun)	occurrence (noun)
an event that recurs at intervals	an event that happens
	an instance of something occurring