servant vs retainer

servant and retainer both are nouns.

Word	Noun	Adjective	Verb	Adverb
servant	Yes	No	No	No
retainer	Yes	No	No	No

As nouns, servant and retainer are synonyms defined as:

servant and retainer: a person working in the service of another (especially in the household)

servant (noun)	retainer (noun)
a person working in the service of another (especially in the household)	a dental appliance that holds teeth (or a prosthesis) in position after orthodontic treatment
in a subordinate position	a person working in the service of another (especially in the household)
	a fee charged in advance to retain the services of someone