haematemesis vs regurgitation

haematemesis and regurgitation both are nouns.

Word	Noun	Adjective	Verb	Adverb
haematemesis	Yes	No	No	No
regurgitation	Yes	No	No	No

As nouns, regurgitation is a hypernym of haematemesis; that is, regurgitation is a word with a broader meaning than haematemesis:

haematemesis: vomiting blood
regurgitation: the reflex act of ejecting the contents of the stomach through the mouth

Other hypernyms of haematemesis include disgorgement, emesis, puking, vomit, vomiting.

haematemesis (noun)	regurgitation (noun)
vomiting blood	the reflex act of ejecting the contents of the stomach through the mouth
	recall after rote memorization
	backflow of blood through a defective heart valve