rumination vs regurgitation

rumination and regurgitation both are nouns.

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

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

rumination: regurgitation of small amounts of food; seen in some infants after feeding
regurgitation: the reflex act of ejecting the contents of the stomach through the mouth

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

rumination (noun)	regurgitation (noun)
regurgitation of small amounts of food; seen in some infants after feeding	the reflex act of ejecting the contents of the stomach through the mouth
(of ruminants) chewing (the cud)	recall after rote memorization
a calm, lengthy, intent consideration	backflow of blood through a defective heart valve