lavatory vs potty

lavatory and potty both are nouns.

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

As nouns, potty is a hypernym of lavatory; that is, potty is a word with a broader meaning than lavatory:

Other hypernyms of lavatory include can, commode, crapper, pot, stool, throne, toilet.

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

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