coming together vs assembly

coming together and assembly both are nouns.

Word	Noun	Adjective	Verb	Adverb
coming together	Yes	No	No	No
assembly	Yes	No	No	No

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

Other hypernyms of coming together include assemblage, gathering.

coming together (noun)	assembly (noun)
the social act of assembling for some common purpose	the social act of assembling
the act of joining together as one	the act of constructing something (as a piece of machinery)
	a group of machine parts that fit together to form a self-contained unit
	a public facility to meet for open discussion
	a unit consisting of components that have been fitted together
	a group of persons who are gathered together for a common purpose