chew the fat vs discourse

chew the fat is not a noun while discourse is a noun.

Word	Noun	Adjective	Verb	Adverb
chew the fat	No	No	Yes	No
discourse	Yes	No	Yes	No

As verbs, discourse is a hypernym of chew the fat; that is, discourse is a word with a broader meaning than chew the fat:

Other hypernyms of chew the fat include converse.

chew the fat (noun)	discourse (noun)
	an extended communication (often interactive) dealing with some particular topic
	extended verbal expression in speech or writing
	an address of a religious nature (usually delivered during a church service)

chew the fat (verb)	discourse (verb)
talk socially without exchanging too much information	talk at length and formally about a topic
	carry on a conversation
	to consider or examine in speech or writing