body waste vs waste matter

body waste and waste matter both are nouns.

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

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

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

Other hypernyms of body waste include waste, waste material, waste product.

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