mammy vs mumma

mammy and mumma both are nouns.

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

As nouns, mammy and mumma are synonyms defined as:

Other synonyms of mammy include ma, mama, mamma, mom, momma, mommy, mum, mummy.

mammy (noun)	mumma (noun)
informal terms for a mother	informal terms for a mother
an offensive term for a Black nursemaid in the southern U.S.