mammary gland vs boob

mammary gland and boob both are nouns.

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

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

mammary gland: milk-secreting organ of female mammals
boob: either of two soft fleshy milk-secreting glandular organs on the chest of a woman

Other hyponyms of mammary gland include dug, bag, udder, bosom, breast, knocker, tit, titty.

mammary gland (noun)	boob (noun)
milk-secreting organ of female mammals	either of two soft fleshy milk-secreting glandular organs on the chest of a woman
	an ignorant or foolish person

mammary gland (verb)	boob (verb)
	commit a faux pas or a fault or make a serious mistake