Imo, nails have to be placed through the nail holes, so forward on the hoof. The pins can be positioned towards the rear.
The pins are attached to the bottom surface of the shoe, not a nail that goes into the hoof wall.
However, my current horse has neither atm.
As above, road nails have to go into a nail hole, whereas the farrier can drill the hole for the pin/stud wherever (usually further back than the last nail hole).
My farrier prefers the studs, as he doesn't think the nail hole is the ideal placement, but he has used a road nails when he wasn't able to drill the holes for a stud.
When he used a road nails he set it in the shoe before nailing on, so the shaft of the nail was cut short and effectively riveted into the shoe, rather than putting an extra nail into the hoof.