conference vs group discussion

conference and group discussion both are nouns.

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

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

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

conference (noun)	group discussion (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