nanny vs mammy

nanny and mammy both are nouns.

Word	Noun	Adjective	Verb	Adverb
nanny	Yes	No	No	No
mammy	Yes	No	No	No

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

Other hyponyms of nanny include dry nurse, amah, wet-nurse, wet nurse, wetnurse.

nanny (noun)	mammy (noun)
female goat	informal terms for a mother
a woman who is the custodian of children	an offensive term for a Black nursemaid in the southern U.S.