excreta vs fecal matter

excreta and fecal matter both are nouns.

Word	Noun	Adjective	Verb	Adverb
excreta	Yes	No	No	No
fecal matter	Yes	No	No	No

As nouns, fecal matter is a hyponym of excreta; that is, fecal matter is a word with a more specific, narrower meaning than excreta:

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

excreta (noun)	fecal matter (noun)
waste matter (as urine or sweat but especially feces) discharged from the body	solid excretory product evacuated from the bowels