bartender vs barkeep

bartender and barkeep both are nouns.

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

As nouns, bartender and barkeep are synonyms defined as:

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

Other synonyms of bartender include barkeeper, mixologist.

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