occasion vs occurrence

occasion and occurrence both are nouns.

Word	Noun	Adjective	Verb	Adverb
occasion	Yes	No	Yes	No
occurrence	Yes	No	No	No

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

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

occasion (noun)	occurrence (noun)
an event that occurs at a critical time	an event that happens
a formal or official social gathering or ceremony of people	an instance of something occurring
a rational motive for a belief or action
an opportunity to do something
the time of a particular event

occasion (verb)	occurrence (verb)
give occasion to