chew the fat vs chat

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

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

As verbs, chew the fat and chat are synonyms defined as:

chew the fat and chat: talk socially without exchanging too much information

chew the fat (noun)	chat (noun)
	songbirds having a chattering call
	birds having a chattering call
	an informal conversation

chew the fat (verb)	chat (verb)
talk socially without exchanging too much information	talk socially without exchanging too much information