bathroom is 'assimilated' American English, British English would be wc, lavatory, toilet, little house, loo, bog, ladies, mens, cloakroom, little girl's room, outhouse, ❤❤❤❤ house etc., if you use the word 'bathroom' in the UK, you would expect to see not just a toilet but a bath in the room as well, particularly in houses that do not have a separate wc (water closet).
According to Duden it's the same word. I also seem to recall hearing someone say 'Ich bin auf der Toilette,' i.e. actually sitting on the porcelain thing. As for the room itself, das Bad, das WC or das Klo always seemed to be the more common expressions when I was traveling over there (it might be amusing and awkward to say one is 'in der Toilette'). It's kind of funny how Duolingo has the porcelain thing in its graphic for the Household unit, but seems so reluctant in both the Spanish and German courses, to actually give us the word for it.