excretion vs faeces

excretion and faeces both are nouns.

Word	Noun	Adjective	Verb	Adverb
excretion	Yes	No	No	No
faeces	Yes	No	No	No

As nouns, faeces is a hyponym of excretion; that is, faeces is a word with a more specific, narrower meaning than excretion:

excretion: waste matter (as urine or sweat but especially feces) discharged from the body
faeces: solid excretory product evacuated from the bowels

excretion (noun)	faeces (noun)
the bodily process of discharging waste matter	solid excretory product evacuated from the bowels
waste matter (as urine or sweat but especially feces) discharged from the body