excretion vs vomitus

excretion and vomitus both are nouns.

Word	Noun	Adjective	Verb	Adverb
excretion	Yes	No	No	No
vomitus	Yes	No	No	No

As nouns, vomitus is a hyponym of excretion; that is, vomitus is a word with a more specific, narrower meaning than excretion:

excretion: waste matter (as urine or sweat but especially feces) discharged from the body
vomitus: the matter ejected in vomiting

excretion (noun)	vomitus (noun)
the bodily process of discharging waste matter	the matter ejected in vomiting
waste matter (as urine or sweat but especially feces) discharged from the body