Ruger's original .44 Magnum was the Blackhawk, a flat-top, three screw single action. It was made concurrently with the Super Blackhawk for awhile, then dropped. For the Ruger Fiftieth anniversery Ruger resurrected the flat top frame, though on the New Model design with transfer bar. The Flat Top Blackhawk .44 Magnum and Super Blackhawk differ primarily that the Super Blackhawk has the ribbed top strap and lowered wide hammer spur. Other features may, or may not, be found on the Super Blackhawk. The Dragoon grip frame is on the 7 1/2" Super Blackhawk, as is the non-fluted cylinder.
As to the frame, the only difference is the rear sight ribs on the top strap.