excretion vs urination

excretion and urination both are nouns.

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

As nouns, urination is a hyponym of excretion; that is, urination is a word with a more specific, narrower meaning than excretion:

Other hyponyms of excretion include defecation, laxation, shitting, incontinence, incontinency, micturition.

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