body waste vs BM

body waste and BM both are nouns.

Word	Noun	Adjective	Verb	Adverb
body waste	Yes	No	No	No
BM	Yes	No	No	No

As nouns, BM is a hyponym of body waste; that is, BM is a word with a more specific, narrower meaning than body waste:

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

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