occasion vs gathering

occasion and gathering both are nouns.

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

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

Other hypernyms of occasion include social event, assemblage.

occasion (noun)	gathering (noun)
an event that occurs at a critical time	the social act of assembling
a formal or official social gathering or ceremony of people	the act of gathering something
a rational motive for a belief or action	sewing consisting of small folds or puckers made by pulling tight a thread in a line of stitching
an opportunity to do something	a group of persons together in one place
the time of a particular event

occasion (verb)	gathering (verb)
give occasion to