fecal matter vs poop

fecal matter and poop both are nouns.

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

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

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

fecal 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