crapper vs lavatory

crapper and lavatory both are nouns.

Word	Noun	Adjective	Verb	Adverb
crapper	Yes	No	No	No
lavatory	Yes	No	No	No

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

Other hyponyms of crapper include flushless toilet, flush toilet, potty chair, potty seat.

crapper (noun)	lavatory (noun)
a plumbing fixture for defecation and urination	a room or building equipped with one or more toilets
	a bathroom sink that is permanently installed and connected to a water supply and drainpipe; where you can wash your hands and face
	a toilet that is cleaned of waste by the flow of water through it