mommy vs mummy

mommy and mummy both are nouns.

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

As nouns, mommy and mummy are synonyms defined as:

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

mommy (noun)	mummy (noun)
informal terms for a mother	a body embalmed and dried and wrapped for burial (as in ancient Egypt)
	informal terms for a mother