mammary gland vs titty

mammary gland and titty both are nouns.

Word	Noun	Adjective	Verb	Adverb
mammary gland	Yes	No	No	No
titty	Yes	No	No	No

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

mammary gland: 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 mammary gland include dug, bag, udder, boob, bosom, breast, knocker, tit.

mammary gland (noun)	titty (noun)
milk-secreting organ of female mammals	either of two soft fleshy milk-secreting glandular organs on the chest of a woman