audience vs group discussion

audience and group discussion both are nouns.

Word	Noun	Adjective	Verb	Adverb
audience	Yes	No	No	No
group discussion	Yes	No	No	No

As nouns, group discussion is a hypernym of audience; that is, group discussion is a word with a broader meaning than audience:

audience: a conference (usually with someone important)
group discussion: a discussion among participants who have an agreed (serious) topic

Other hypernyms of audience include conference.

audience (noun)	group discussion (noun)
a conference (usually with someone important)	a discussion among participants who have an agreed (serious) topic
a gathering of spectators or listeners at a (usually public) performance
the part of the general public interested in a source of information, entertainment, or a product/service
an opportunity to state your case and be heard