restroom vs bathroom

restroom and bathroom both are nouns.

Word	Noun	Adjective	Verb	Adverb
restroom	Yes	No	No	No
bathroom	Yes	No	No	No

As nouns, bathroom is a hypernym of restroom; that is, bathroom is a word with a broader meaning than restroom:

Other hypernyms of restroom include facility, can, john, lav, lavatory, privy, toilet.

restroom (noun)	bathroom (noun)
a toilet that is available to the public	a room (as in a residence) containing a bathtub or shower and usually a washbasin and toilet
	a room or building equipped with one or more toilets