excrement vs piss

excrement and piss both are nouns.

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

As nouns, piss is a hyponym of excrement; that is, piss 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
piss: liquid excretory product

excrement (noun)	piss (noun)
waste matter (as urine or sweat but especially feces) discharged from the body	informal terms for urination
	liquid excretory product

excrement (verb)	piss (verb)
	eliminate urine