chatelaine vs mistress

chatelaine and mistress both are nouns.

Word	Noun	Adjective	Verb	Adverb
chatelaine	Yes	No	No	No
mistress	Yes	No	No	No

As nouns, mistress is a hypernym of chatelaine; that is, mistress is a word with a broader meaning than chatelaine:

chatelaine (noun)	mistress (noun)
a chain formerly worn at the waist by women; for carrying a purse or bunch of keys etc.	a woman master who directs the work of others
the mistress of a chateau or large country house	an adulterous woman; a woman who has an ongoing extramarital sexual relationship with a man
	a woman schoolteacher (especially one regarded as strict)