excretion vs waste material

excretion and waste material both are nouns.

Word	Noun	Adjective	Verb	Adverb
excretion	Yes	No	No	No
waste material	Yes	No	No	No

As nouns, waste material is a hypernym of excretion; that is, waste material is a word with a broader meaning than excretion:

excretion: waste matter (as urine or sweat but especially feces) discharged from the body
waste material: any materials unused and rejected as worthless or unwanted

Other hypernyms of excretion include waste, waste matter, waste product.

excretion (noun)	waste material (noun)
the bodily process of discharging waste matter	any materials unused and rejected as worthless or unwanted
waste matter (as urine or sweat but especially feces) discharged from the body