mother's boy vs mamma's boy

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

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

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

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

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

mother'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