mamma's boy vs mother's boy

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

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

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

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

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

mamma's boy (noun)	mother'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