mama's boy vs mamma's boy

mama's boy and mamma's boy both are nouns.

Word	Noun	Adjective	Verb	Adverb
mama's boy	Yes	No	No	No
mamma's boy	Yes	No	No	No

As nouns, mama's boy and mamma's boy are synonyms defined as:

mama's boy and mamma's boy: a boy excessively attached to his mother; lacking normal masculine interests

Other synonyms of mama's boy include mother's boy.

mama's boy (noun)	mamma's boy (noun)
a boy excessively attached to his mother; lacking normal masculine interests	a boy excessively attached to his mother; lacking normal masculine interests