PP focuses on weight loss, while PPLP includes weight loss but also talks about overall health.

One of the main "practical" differences is that in PP they give you a complicated formula for calculating your daily protein needs, while in the 2nd book they just give you a chart based on height, weight, and gender. The chart rounds everything up- which means that if you follow the chart your'e definitely getting at least the amount you would have calculated.

However, I had a hard time getting in enough protein based on the chart, and I was getting seriously sick of PP and ready to give up on it altogether, when I realized I was easily (by following my own hunger cues) getting enough protein based on the calculations. So I reset my Fitday protein minimum to reflect the calculated protein needs- some days I eat just enough, some days I'm way over, but the pressure is off.

I wish they'd included the calculation formulas AND the charts in PPLP, to give people the choice of which method to choose.