kvetch vs nag

kvetch and nag both are nouns.

Word	Noun	Adjective	Verb	Adverb
kvetch	Yes	No	Yes	No
nag	Yes	No	Yes	No

As verbs, nag is a hyponym of kvetch; that is, nag is a word with a more specific, narrower meaning than kvetch:

kvetch (noun)	nag (noun)
(Yiddish) a nagging complaint	an old or over-worked horse
(Yiddish) a constant complainer	someone (especially a woman) who annoys people by constantly finding fault

kvetch (verb)	nag (verb)
express complaints, discontent, displeasure, or unhappiness	remind or urge constantly
	bother persistently with trivial complaints
	worry persistently