faecal matter vs poop

faecal matter and poop both are nouns.

Word	Noun	Adjective	Verb	Adverb
faecal matter	Yes	No	No	No
poop	Yes	No	No	No

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

Other hyponyms of faecal matter include dog do, dog shit, dog turd, doggy do, crap, dirt, shit, shite, turd, droppings, dung, muck, meconium, melaena, melena.

faecal matter (noun)	poop (noun)
solid excretory product evacuated from the bowels	the rear part of a ship
	slang terms for inside information
	a stupid foolish person
	obscene terms for feces