public lavatory vs wash room

public lavatory and wash room both are nouns.

Word	Noun	Adjective	Verb	Adverb
public lavatory	Yes	No	No	No
wash room	Yes	No	No	No

As nouns, public lavatory and wash room are synonyms defined as:

Other synonyms of public lavatory include comfort station, convenience, public convenience, public toilet, restroom, toilet facility.

public lavatory (noun)	wash room (noun)
a toilet that is available to the public	a toilet that is available to the public