session vs congress

session and congress both are nouns.

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

As nouns, congress is a hypernym of session; that is, congress is a word with a broader meaning than session:

Other hypernyms of session include coming together, meeting.

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