urinator vs bed wetter

urinator and bed wetter both are nouns.

Word	Noun	Adjective	Verb	Adverb
urinator	Yes	No	No	No
bed wetter	Yes	No	No	No

As nouns, bed wetter is a hyponym of urinator; that is, bed wetter is a word with a more specific, narrower meaning than urinator:

urinator: a person who urinates
bed wetter: someone suffering from enuresis; someone who urinates while asleep in bed

Other hyponyms of urinator include bedwetter, wetter.

urinator (noun)	bed wetter (noun)
a person who urinates	someone suffering from enuresis; someone who urinates while asleep in bed