...and the green box TSP Substitute PF is phosphate free...I thought that was the only difference between the two?
OK, before anyone makes a snide remark here I'll correct myself...duh...of COURSE a phosphate-free version of TSP is NOT TSP but a completely different set of chemical ingredients.
If I remember correctly, PBW is phosphate-free and an alkali, similar to TSP Substitute PF. In doing a brief search, it appears the chemical makeup of both products is proprietary but I'm sure someone out there has "inside" info on both.
Gail