crowd together vs mob

crowd together is not a noun while mob is a noun.

Word	Noun	Adjective	Verb	Adverb
crowd together	No	No	Yes	No
mob	Yes	No	Yes	No

As verbs, mob is a hyponym of crowd together; that is, mob is a word with a more specific, narrower meaning than crowd together:

Other hyponyms of crowd together include mass, overcrowd, pour, pullulate, stream, swarm, teem, herd, jam, pack, pile, throng.

crowd together (noun)	mob (noun)
	a disorderly crowd of people
	an association of criminals
	a loose affiliation of gangsters in charge of organized criminal activities

crowd together (verb)	mob (verb)
to gather together in large numbers	press tightly together or cram