The "Shield-On" indicator means the blade is not exposed. The "Shield-off" indicator means that the blade is exposed.
Pressure from the palm of the hand during insertion serves as a "lock" to reveal the blade during insertion through the peritoneum. You will hear an audible click as the blade is revealed.
Once through peritoneum, you should feel a change in tension and can remove pressure from your palm.
The differences are in the obturators. The cannula's and seal housings are essentially the same. RPF has a pyramidal blade and conventional safety shield, where as the V² has a V-shaped blade and parabolic-shaped safety shield.