An FWD vs RWD car,using exact same chassis (thought its not possible) having same power etc, everything the same, except for the traction layout, the RWD one will be slightly heavyer due to its extra parts to transfer power to the rear.
RWD basics advantages that i know are, the better handling on corners,mainly tigheter nes, when the FWD would be showing understeer,at the same point the RWD one would be turning in to out quite faster due to its better balance/more use of the rear to help turning the car, and more traction during aceleration due to weight transition, since weight is transfered to the back of the car while acelerating,and more balanced wear of tires. (i wont talk about advanced stuff since its not needed to)
RWD basics disavantages that i know are,some loss of power due to the extra parts to transmit the power to the rear axle, and all the extra parts and weight at the rear.