keeper vs sitter

keeper and sitter both are nouns.

Word	Noun	Adjective	Verb	Adverb
keeper	Yes	No	No	No
sitter	Yes	No	No	No

As nouns, sitter is a hyponym of keeper; that is, sitter is a word with a more specific, narrower meaning than keeper:

keeper (noun)	sitter (noun)
one having charge of buildings or grounds or animals	a domestic hen ready to brood
someone in charge of other people	a person engaged to care for children when the parents are not home
	an organism (person or animal) that sits
	a person who poses for a painter or sculptor