house servant vs retainer

house servant and retainer both are nouns.

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

As nouns, retainer is a hypernym of house servant; that is, retainer is a word with a broader meaning than house servant:

house servant: a servant who is paid to perform menial tasks around the household
retainer: a person working in the service of another (especially in the household)

Other hypernyms of house servant include servant.

house servant (noun)	retainer (noun)
a servant who is paid to perform menial tasks around the household	a dental appliance that holds teeth (or a prosthesis) in position after orthodontic treatment
	a person working in the service of another (especially in the household)
	a fee charged in advance to retain the services of someone