They seem pretty similar to me from reading posts and discussions. How do they differ?

I haven't read Schwarzbein, but from what I've heard, it's higher in carbs and emphasizes overall health first, weight loss secondary. It allows for more carbs but eliminates caffeine, artificial sweeteners, and other no-no's that Protein Power is a little more lenient with.

...at least that's what I've read here at the forum. If anyone can correct me, please do.

As Kristine noted, SP deals with hormonal balance and once your hormones are balanced, everything - including fat loss - will fall in to place. Ketosis is not part of the SP plan. With PP it's not discussed but it definitely happens. PP is a ketogenic diet.

15 grams of carbs per meal are allowed on Schwarzbein. PP starts at 30 grams a day and you figure out what your adequate protein intake is for a day.

The link to a synopsis of the plans is here. They also have websites with more info.

Karen