ACTH vs internal secretion

ACTH and internal secretion both are nouns.

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

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

ACTH: a hormone produced by the anterior pituitary gland that stimulates the adrenal cortex
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 ACTH include endocrine, hormone.

ACTH (noun)	internal secretion (noun)
a hormone produced by the anterior pituitary gland that stimulates the adrenal cortex	the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect