The biggest difference between the S2 and the S2+ is the size of the reflector. The S2 is much deeper than the S2+, so depending on the LED, the S2 can throw farther. You can get either reflector in orange peel (OP) or smooth.
7135 refers to driver chips. More of them give more current. This is usually listed on the Convoy site with flashlights that have 7135 options:
- 7135*3 output current 1050mA
- 7135*4 output current 1400mA
- 7135*6 output current 2100mA
- 7135*8 output current 2800mA
Biscotti is driver firmware.