hypophysectomy vs extirpation

hypophysectomy and extirpation both are nouns.

Word	Noun	Adjective	Verb	Adverb
hypophysectomy	Yes	No	No	No
extirpation	Yes	No	No	No

As nouns, extirpation is a hypernym of hypophysectomy; that is, extirpation is a word with a broader meaning than hypophysectomy:

Other hypernyms of hypophysectomy include ablation, cutting out, excision.

hypophysectomy (noun)	extirpation (noun)
surgical removal of the pituitary gland	surgical removal of a body part or tissue
	the act of pulling up or out; uprooting; cutting off from existence