millionairess vs wealthy person

millionairess and wealthy person both are nouns.

Word	Noun	Adjective	Verb	Adverb
millionairess	Yes	No	No	No
wealthy person	Yes	No	No	No

As nouns, wealthy person is a hypernym of millionairess; that is, wealthy person is a word with a broader meaning than millionairess:

Other hypernyms of millionairess include have, rich person, adult female, woman.

millionairess (noun)	wealthy person (noun)
a woman millionaire	a person who possesses great material wealth