chit-chat vs discourse

chit-chat and discourse both are nouns.

Word	Noun	Adjective	Verb	Adverb
chit-chat	Yes	No	Yes	No
discourse	Yes	No	Yes	No

As verbs, discourse is a hypernym of chit-chat; that is, discourse is a word with a broader meaning than chit-chat:

Other hypernyms of chit-chat include converse.

chit-chat (noun)	discourse (noun)
light informal conversation for social occasions	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)

chit-chat (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