pituitary vs ductless gland

pituitary and ductless gland both are nouns.

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

As nouns, ductless gland is a hypernym of pituitary; that is, ductless 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
ductless gland: any of the glands of the endocrine system that secrete hormones directly into the bloodstream

Other hypernyms of pituitary include endocrine, endocrine gland.

pituitary (noun)	ductless 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)	ductless gland (adjective)
of or relating to the pituitary gland