congress vs session

congress and session both are nouns.

Word	Noun	Adjective	Verb	Adverb
congress	Yes	No	No	No
session	Yes	No	No	No

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

Other hyponyms of congress include rendezvous, socialisation, socialising, socialization, socializing, visit, visit, visit.

congress (noun)	session (noun)
the social act of assembling for some common purpose	a meeting devoted to a particular activity
a meeting of elected or appointed representatives	a meeting for execution of a group's functions
a national legislative assembly	a meeting of spiritualists
	the time during which a school holds classes