mistress vs chatelaine

mistress and chatelaine both are nouns.

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

As nouns, chatelaine is a hyponym of mistress; that is, chatelaine is a word with a more specific, narrower meaning than mistress:

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