hypophysectomy vs ablation

hypophysectomy and ablation both are nouns.

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

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

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

hypophysectomy (noun)	ablation (noun)
surgical removal of the pituitary gland	surgical removal of a body part or tissue
	the erosive process that reduces the size of glaciers