They are not the same. RS looks at different religions and their beliefs, and how they tackle difficult topics. Philosophy and Ethics looks at ethical and philosophical questions -- for example, does a man, locked in a room, but doesn't want to leave the room and doesn't know it's locked, still have free will? They are both essay-based and I think the exams are rather long and strenuous, but yes they are counted as 'hard' subjects because of the debate and thinking processes involved.