small talk vs chat

small talk and chat both are nouns.

Word	Noun	Adjective	Verb	Adverb
small talk	Yes	No	No	No
chat	Yes	No	Yes	No

As nouns, chat is a hypernym of small talk; that is, chat is a word with a broader meaning than small talk:

Other hypernyms of small talk include confab, confabulation, schmoose, schmooze.

small talk (noun)	chat (noun)
light informal conversation for social occasions	songbirds having a chattering call
	birds having a chattering call
	an informal conversation

small talk (verb)	chat (verb)
	talk socially without exchanging too much information