owner vs proprietor

owner and proprietor both are nouns.

Word	Noun	Adjective	Verb	Adverb
owner	Yes	No	No	No
proprietor	Yes	No	No	No

As nouns, owner and proprietor are synonyms defined as:

owner and proprietor: (law) someone who owns (is legal possessor of) a business

owner (noun)	proprietor (noun)
(law) someone who owns (is legal possessor of) a business	(law) someone who owns (is legal possessor of) a business
a person who owns something