The latest Rapide are out and out aero wheels - 51mm deep at the front and 60mm deep at the rear. But that doesn't mean they're carrying excess weight, a pair come in at a quoted 1400g (front: 649g, rear 751g).
The days of simply copying a rim profile for front and rear are long behind us in this era of aero optimisation. The profiles here are shaped for their specific jobs, with the front designed to cope with gusts of wind without affecting handling and stability (Roval claim they're 25% better than the CLX 50 in this respect).
The rear is shaped for minimal drag, and is also narrower (30mm external width, compared to 35mm at the front).