group discussion vs conference

group discussion and conference both are nouns.

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

As nouns, group discussion and conference are synonyms defined as:

group discussion and conference: a discussion among participants who have an agreed (serious) topic

group discussion (noun)	conference (noun)
a discussion among participants who have an agreed (serious) topic	a discussion among participants who have an agreed (serious) topic
	a prearranged meeting for consultation or exchange of information or discussion (especially one with a formal agenda)
	an association of sports teams that organizes matches for its members