baroness vs peeress

baroness and peeress both are nouns.

Word	Noun	Adjective	Verb	Adverb
baroness	Yes	No	No	No
peeress	Yes	No	No	No

As nouns, peeress is a hypernym of baroness; that is, peeress is a word with a broader meaning than baroness:

baroness: a noblewoman who holds the rank of baron or who is the wife or widow of a baron
peeress: a woman of the peerage in Britain

Other hypernyms of baroness include Lady, noblewoman.

baroness (noun)	peeress (noun)
a noblewoman who holds the rank of baron or who is the wife or widow of a baron	a woman of the peerage in Britain