excrement vs waste material

excrement and waste material both are nouns.

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

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

excrement: 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 excrement include waste, waste matter, waste product.

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