endocrine gland vs ductless gland

endocrine gland and ductless gland both are nouns.

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

As nouns, endocrine gland and ductless gland are synonyms defined as:

endocrine gland and ductless gland: any of the glands of the endocrine system that secrete hormones directly into the bloodstream

Other synonyms of endocrine gland include endocrine.

endocrine gland (noun)	ductless gland (noun)
any of the glands of the endocrine system that secrete hormones directly into the bloodstream	any of the glands of the endocrine system that secrete hormones directly into the bloodstream