serving girl vs servant

serving girl and servant both are nouns.

Word	Noun	Adjective	Verb	Adverb
serving girl	Yes	No	No	No
servant	Yes	No	No	No

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

serving girl: a girl who is a servant
servant: a person working in the service of another (especially in the household)

Other hypernyms of serving girl include retainer.

serving girl (noun)	servant (noun)
a girl who is a servant	a person working in the service of another (especially in the household)
	in a subordinate position