excretion vs voiding

excretion and voiding both are nouns.

Word	Noun	Adjective	Verb	Adverb
excretion	Yes	No	No	No
voiding	Yes	No	No	No

As nouns, excretion and voiding are synonyms defined as:

Other synonyms of excretion include elimination, evacuation, excreting.

excretion (noun)	voiding (noun)
the bodily process of discharging waste matter	the bodily process of discharging waste matter
waste matter (as urine or sweat but especially feces) discharged from the body