insulin vs internal secretion

insulin and internal secretion both are nouns.

Word	Noun	Adjective	Verb	Adverb
insulin	Yes	No	No	No
internal secretion	Yes	No	No	No

As nouns, internal secretion is a hypernym of insulin; that is, internal secretion is a word with a broader meaning than insulin:

insulin: hormone secreted by the isles of Langerhans in the pancreas; regulates storage of glycogen in the liver and accelerates oxidation of sugar in cells
internal secretion: the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect

Other hypernyms of insulin include endocrine, hormone, hypoglycaemic agent, hypoglycemic agent.

insulin (noun)	internal secretion (noun)
hormone secreted by the isles of Langerhans in the pancreas; regulates storage of glycogen in the liver and accelerates oxidation of sugar in cells	the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect