The SS #2 has detachable straps, so that one may change them out for different width belts. The SS #2 also has a "sweat/shirt guard" that extends up between the holstered pistol and the users side (most folks seem to like these guards. I don't).
The Summer Special has fixed belt loops and, unless Tony has changed it, NO sweat/shirt guard.
I believe that the SS #2 is available in "smooth-side-out" construction. The Summer Special is rough-out only.
If you have questions about the superb line of holsters put out by the Sparks team, give them a call. These guys are pistol carriers and shooters. They have the experience to answer any questions you may have.