toilet vs lavatory

toilet and lavatory both are nouns.

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

As nouns, toilet and lavatory are synonyms defined as:

toilet and lavatory: a room or building equipped with one or more toilets

Other synonyms of toilet include bathroom, can, john, lav, privy.

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

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

toilet (noun)	lavatory (noun)
the act of dressing and preparing yourself	a room or building equipped with one or more toilets
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 plumbing fixture for defecation and urination	a toilet that is cleaned of waste by the flow of water through it
misfortune resulting in lost effort or money