Although these three words have the same idea (banheiro), they have different uses.
Bathroom /ˈbɑːθ.rʊm/ - noun
1. [C] a room with a bath and/or shower and often a toilet
an ensuite bathroom (= a bathroom joined to a bedroom)
Toilet /ˈtɔɪ.lət/ - noun
1. [C] a bowl-shaped device with a seat which you sit on or stand near when emptying the body of urine or solid waste, or another device used for this purpose
Don't forget to flush the toilet.
2. [C] UK (US bathroom ) a room with a toilet in it
Someone's in the toilet.
Restroom /ˈrest.rʊm/ - noun
[C] mainly US a room with toilets that is in a public place, for example in a restaurant
Teacher, may I go to the toilet?
P.S. [ C or U ] = countable or uncountable
