mamma vs titty

mamma and titty both are nouns.

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

As nouns, titty is a hyponym of mamma; that is, titty is a word with a more specific, narrower meaning than mamma:

mamma: milk-secreting organ of female mammals
titty: either of two soft fleshy milk-secreting glandular organs on the chest of a woman

Other hyponyms of mamma include dug, bag, udder, boob, bosom, breast, knocker, tit.

mamma (noun)	titty (noun)
milk-secreting organ of female mammals	either of two soft fleshy milk-secreting glandular organs on the chest of a woman
informal terms for a mother