pituitary vs endocrine gland

pituitary and endocrine gland both are nouns.

Word	Noun	Adjective	Verb	Adverb
pituitary	Yes	Yes	No	No
endocrine gland	Yes	No	No	No

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

pituitary: the master gland of the endocrine system; located at the base of the brain
endocrine gland: any of the glands of the endocrine system that secrete hormones directly into the bloodstream

Other hypernyms of pituitary include ductless gland, endocrine.

pituitary (noun)	endocrine gland (noun)
the master gland of the endocrine system; located at the base of the brain	any of the glands of the endocrine system that secrete hormones directly into the bloodstream

pituitary (adjective)	endocrine gland (adjective)
of or relating to the pituitary gland