مرحاض=toilet حمام=bathroom for exsample انا سوف اذهب الى الحمام لتنظيف المرحاض i will go to the bathroom to clean the toilet انت تذهب الى الحمام لاستخدام المرحاض you go to the bathroom to use toilet i hope you understand me

حمام : means bathroom. but it's kind of informal, but don't worry,it's a perfectly fine word. but some people use this word as (shower) and (bathroom) at the same time. so don't be confused. you can also use the phrase دورة المياه or دورات المياه as a phrase that any Arabian would understand and it's frequently more used in resturants or so. مرحاض : is more like (toilet)

حمام in some arabic dialect mean toilet, other dialect mean bathroom in reality hammam is a traditional bath, where is there a hot water, naturel in general, and there is a big hot room, and small rooms, where peapole can take a shaower individualy, have a massage in the big room http://www.google.fr/imgres?imgurl=http://www.syriasteps.com/archive/image/hamam%2520(8).jpg&imgrefurl=http://www.sham-cafe.net/vb/showthread.php%3Ft%3D101020&usg=__VcvxQ5G1Spn2NEPAQGEzRSgvjL8=&h=300&w=400&sz=143&hl=fr&start=13&zoom=1&tbnid=n3kikuT22POA7M:&tbnh=93&tbnw=124&ei=IUgLT8OAN8WdOoD1rbgB&prev=/search%3Fq%3D%25D8%25AD%25D9%2585%25D9%2591%25D8%25A7%25D9%2585%2B%25D8%25B4%25D8%25A7%25D9%2585%26hl%3Dfr%26sa%3DX%26biw%3D1366%26bih%3D572%26tbm%3Disch%26prmd%3Dimvns&itbs=1