excrement vs vomitus

excrement and vomitus both are nouns.

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

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

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

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