Tons of differences, not even the same bike. RC51 is a surgeon's tool, while a Super Hawk is a Gulf War Medic's bandage.
I have a Super Hawk. I'd have to say one is race ready, the other is street ready. My S.H. has a teeny tiny little fuel tank, but sounds awesome with Jardine Hi-mounts.
Hopefully Randy will chime in and tell you how impressive an RC51 is.