Real r&b is not this sh1t that people like chris brown and britney spears and other dumb people make.
R&B is the good old 90's stuff. Music is not how it used to be. Thats why i mostly spin house music.
R&B is rhythm and blues. It mostly have a smooth beat with somewhat emotional lyrics (at least thats how it used to be).
Rap is a part of hip-hop (A PART OF IT), and usually have a similar beat or more up-tempo, with sometimes gangster lyrics, rhymes about how hard their life was, or the way they party, etc etc.
And as for techno, its way way WAY different (i shouldnt even explain).
See my name?