The Basic Forehand grip is in principle very similar to the corresponding backhand grip. The middle finger of the throwing hand is inside the rim and the index finger is extended towards the centre of the disc for support. The advantage of this method is control. The disadvantage is a corresponding loss of power, because the spreading of the fingers makes it impossible to cock the wrist back as far just before release.
The Power grip of the forehand has the index finger next to the middle finger and hard up against the rim. This grip increases power since the wrist can now be cocked back further and more snap imparted no the disc. As expected, there is a loss of control as there is no finger to support the disc. The disc has a tendency to wobble up and down, and this can reduce distance if the disc and the wrist are not at the same angle at release.