In program zero it says to do Frankenstein squats, I was just wondering what is the difference between each squat and if I could do back squats to replace the Frankenstein squats ?
Progressions, my dear friend. Frank squats teach you to rest the bar on the shoulders while you squat, which later will help with normal front squats. Back squats put the bar behind the neck which requires more forward lean of the torso and thus more shear stress on the spine.
Even if you’re a proficient lifter, testing your basic progressions is a very good habit. Post a video!