collection vs gathering

collection and gathering both are nouns.

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

As nouns, gathering is a hyponym of collection; that is, gathering is a word with a more specific, narrower meaning than collection:

collection (noun)	gathering (noun)
the act of gathering something together	the social act of assembling
a publication containing a variety of works	the act of gathering something
request for a sum of money	sewing consisting of small folds or puckers made by pulling tight a thread in a line of stitching
several things grouped together or considered as a whole	a group of persons together in one place