potty vs lavatory

potty and lavatory both are nouns.

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

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

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

potty (noun)	lavatory (noun)
a receptacle for urination or defecation in the bedroom	a room or building equipped with one or more toilets
a plumbing fixture for defecation and urination	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

potty (adjective)	lavatory (adjective)
slightly intoxicated
marked by foolish or unreasoning fondness
(British informal) trivial