Given the same sights and same stock, a rifle would have more drop than a gun. This is why the pistol grip is seen more often on a rifle than on a gun, while the gun is more likely to have a straight stock, especially British guns. The idea is that with a rifle, the game comes in under the gun, while with a shotgun it comes in over the gun. Where this idea gets a little weaker is in rough shooting where the bird is likely to be going away. Fit is more critical with a gun which is pointed while a rfile is aimed. (Unless you have a charging bull at 20 paces, then rifle fit starts getting a little more critical.)