There's quite a difference between the two.
PH is the most endurance-based weight workout Cathe has, IMO, and is very 'body pump-like". Each exercise is cued to one song, and you do one exercise throughout the song (with the exception of squats, where you first do squats, then plié squats, about 120 reps total).
MM is endurance and strength-based, IMO, and you can use heavier weights with it. There is more variety of exercises for each body part.
I think both workouts are worth having.