body waste vs piss

body waste and piss both are nouns.

Word	Noun	Adjective	Verb	Adverb
body waste	Yes	No	No	No
piss	Yes	No	Yes	No

As nouns, piss is a hyponym of body waste; that is, piss is a word with a more specific, narrower meaning than body waste:

body waste: waste matter (as urine or sweat but especially feces) discharged from the body
piss: liquid excretory product

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

body waste (verb)	piss (verb)
	eliminate urine