multitude vs concourse

multitude and concourse both are nouns.

Word	Noun	Adjective	Verb	Adverb
multitude	Yes	No	No	No
concourse	Yes	No	No	No

As nouns, multitude and concourse are synonyms defined as:

Other synonyms of multitude include throng.

multitude (noun)	concourse (noun)
a large gathering of people	a coming together of people
the common people generally	a wide hallway in a building where people can walk
a large indefinite quantity	a large gathering of people