pee vs excretion

pee and excretion both are nouns.

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

As nouns, excretion is a hypernym of pee; that is, excretion is a word with a broader meaning than pee:

pee: liquid excretory product
excretion: waste matter (as urine or sweat but especially feces) discharged from the body

Other hypernyms of pee include body waste, excrement, excreta, excretory product.

pee (noun)	excretion (noun)
informal terms for urination	the bodily process of discharging waste matter
liquid excretory product	waste matter (as urine or sweat but especially feces) discharged from the body

pee (verb)	excretion (verb)
eliminate urine