mamma vs udder

mamma and udder both are nouns.

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

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

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

mamma (noun)	udder (noun)
milk-secreting organ of female mammals	mammary gland of bovids (cows and sheep and goats)
informal terms for a mother