They are both great combos. The Pro DFC is just that.. is has a Direct Flight control head and the pro v2 has the head with the washout arms. They both look different but both are designed to keep proper phase with the rotor head. They how ever have different electronics as a combo and the main gear are different. The DFC has a main 121t main gear with a 12t pinion in its combo and the V2 has a 150t main and a 15t pinion. It seems to have the same gear ratio. I see no difference in my opinion.
The dfc has a direct link from the rotor grip to the swash which eliminates the second set of intermediate links (radius arms) from the main shaft to the swash as is the set up on the pro V2. Consequently, the dfc head is lower utilizing a shorter main shaft with a lower center of gravity allowing for less resistance during flight maneuvers.