thyroid gland vs endocrine

thyroid gland and endocrine both are nouns.

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

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

thyroid gland: located near the base of the neck
endocrine: any of the glands of the endocrine system that secrete hormones directly into the bloodstream

Other hypernyms of thyroid gland include ductless gland, endocrine gland.

thyroid gland (noun)	endocrine (noun)
located near the base of the neck	the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
	any of the glands of the endocrine system that secrete hormones directly into the bloodstream

thyroid gland (adjective)	endocrine (adjective)
	of or belonging to endocrine glands or their secretions