son of screamer question

[burningwater]

I built this on a breadboard - one question I have is in comparing it to the normal TS schematic, I noticed the volume pot lug goes to VR on the TS but to ground on the son. I hooked up a toggle to see the difference and the it seems to just be changing the sweep of the pot (volume is lower when going to vr)

Can anyone explain whats happening here and if there will be tonal differences as well as volume?