Posted: Jun 14, 2016 4:11 pm
by abstract.ipz
I live in the U.S. and in my experience on signs and in more formal situations it's called a restroom but otherwise called a bathroom although either can be used they both refer to the place you go to relieve yourself.

P.S neither really make sense as ( as least in public) bathrooms are not use for bathing and usually people don't just take naps in the rest room.