calling together vs gathering

calling together and gathering both are nouns.

Word	Noun	Adjective	Verb	Adverb
calling together	Yes	No	No	No
gathering	Yes	No	No	No

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

Other hypernyms of calling together include assemblage, assembly.

calling together (noun)	gathering (noun)
the act of convoking	the social act of assembling
	the act of gathering something
	sewing consisting of small folds or puckers made by pulling tight a thread in a line of stitching
	a group of persons together in one place