mamma vs mammy

mamma and mammy both are nouns.

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

As nouns, mamma and mammy are synonyms defined as:

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

mamma (noun)	mammy (noun)
milk-secreting organ of female mammals	informal terms for a mother
informal terms for a mother	an offensive term for a Black nursemaid in the southern U.S.