STH vs internal secretion

STH and internal secretion both are nouns.

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

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

STH: a hormone produced by the anterior pituitary gland; promotes growth in humans
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 STH include endocrine, hormone.

STH (noun)	internal secretion (noun)
a hormone produced by the anterior pituitary gland; promotes growth in humans	the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect