Silver bullets differ from lead bullets in several respects. Lead has a 10% higher density than silver, so a silver bullet will have a little less mass than a lead bullet of identical dimensions. Pure silver is less malleable than lead and falls between lead and copper in terms of hardness (1.5 < 2.5 < 3.0 Mohs) and shear modulus (5.6 < 30 < 48 GPa). A silver bullet accepts the rifling of a gun barrel.
The terminal impact is somewhat speculative and will depend on a variety of factors including bullet size and shape, flight distance, and target material. At short ranges, the silver bullet will most likely give better penetration due to its higher shear modulus, and will not deform as much as a lead bullet. modern weapons and a rifled barrel will readily accept a silver bullet or pellet.