They are not radically different. The PS splits are grouped differently for upper body, there are a few different exercises, there's less equipment involved (no stability ball or band--though ankle weights are optional; Cathe shows a different method available), and there may be about 5 minutes less in a couple of the workouts. Abdominals are included in two of the programs. In my opinion, both GS and PS focus on hypertrophy-strength (10-12 reps with about 30 secs. rest). I wouldn't say you absolutely need them but the series is very enjoyable. Have you checked any clips?