rear end vs excrement

rear end and excrement both are nouns.

Word	Noun	Adjective	Verb	Adverb
rear end	Yes	No	No	No
excrement	Yes	No	No	No

rear end (noun)	excrement (noun)
the fleshy part of the human body that you sit on	waste matter (as urine or sweat but especially feces) discharged from the body