boob vs mammary gland

boob and mammary gland both are nouns.

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

As nouns, mammary gland is a hypernym of boob; that is, mammary gland is a word with a broader meaning than boob:

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

Other hypernyms of boob include mamma.

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

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