bartender vs barkeeper

bartender and barkeeper both are nouns.

Word	Noun	Adjective	Verb	Adverb
bartender	Yes	No	No	No
barkeeper	Yes	No	No	No

As nouns, bartender and barkeeper are synonyms defined as:

bartender and barkeeper: an employee who mixes and serves alcoholic drinks at a bar

Other synonyms of bartender include barkeep, mixologist.

bartender (noun)	barkeeper (noun)
an employee who mixes and serves alcoholic drinks at a bar	an employee who mixes and serves alcoholic drinks at a bar