There was the 357 Supermag and the 357 Maximum.
Case length for the 357 maximum is 1.605 inch while for the SuperMag it is 1.610 inch, not much difference there, but the OAL for the 357 Maximum is 1.990 inch while the SuperMag is 2.080 inch, a HUGE difference.
Elgin Gates developed the 357 Supermag, it was designed to shoot a heavier than normal bullet at slightly higher than normal 357 velocities for silhouette shooting.
Ruger and Remington came up with the 357 Maximum, Ruger did not want to make the revolver window long enough to accommodate the SuperMag. The case is almost as long as the cylinder so there is not much room for a heavy bullet with out seating deep and using up powder room. The first factory load had a light bullet driven to super high velocities using a massive charge of slow ball powder. This is a recipe for erosion problems and it stunk for silhouette shooting too.