The main difference between the two is that the Hyper 7 RTR uses a C-hub design while the PBS uses the Pivot Ball Suspension. As you mentioned, the PBS comes with both the pullstart and the starterbox. The PBS also has a center Spider gear where the Hyper 7 RTR uses a standard center diff. The only other REAL difference is that the PBS uses a combination of CVA's and Universals while the Hyper 7 RTR uses CVA's only. Both are also steel spur designs.

Outside of that, the differences are cosmetic in that they Hyper 7 RTR has a different color shceme, wheels and tires. That's about it!