beginning vs occurrence

beginning and occurrence both are nouns.

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

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

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

beginning (noun)	occurrence (noun)
the act of starting something	an event that happens
the first part or section of something	an instance of something occurring
the event consisting of the start of something
the place where something begins, where it springs into being
the time at which something is supposed to begin

beginning (adjective)	occurrence (adjective)
serving to begin