What is the difference between a Redhawk & a Super Redhawk?
Basically, the primary difference is the frame extension that surrounds the first couple inches of barrel on the SRH, that also serves as scope mounting platform.
Also the grip frames are different. The Redhawk has a grip frame similar to a single action revolver with panels on the sides. The SRH has a grip "stud" similar to the GP100.
The overall size is the same and cylinders can interchange between them.