excretion vs waste product

excretion and waste product both are nouns.

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

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

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

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

excretion (noun)	waste product (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