mamma vs mummy

mamma and mummy both are nouns.

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

As nouns, mamma and mummy are synonyms defined as:

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

mamma (noun)	mummy (noun)
milk-secreting organ of female mammals	a body embalmed and dried and wrapped for burial (as in ancient Egypt)
informal terms for a mother	informal terms for a mother