billionaire vs wealthy person

billionaire and wealthy person both are nouns.

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

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

billionaire: a very rich person whose material wealth is valued at more than a billion dollars
wealthy person: a person who possesses great material wealth

Other hypernyms of billionaire include have, rich person.

billionaire (noun)	wealthy person (noun)
a very rich person whose material wealth is valued at more than a billion dollars	a person who possesses great material wealth