Either are quite adequate for hunting any game species found in North America. The .500 has roughly twice the muzzle energy that the .50-70 Model 1866 Springfield did that "Buffalo Bill" Cody used to kill the 1200+ Bison that got him his moniker.

They are roughly equal. The 460 will give higher velocity than the 500 creating approximately the same muzzle energy. If you expect to re-load for either, bullets for the 460 are somewhat less expensive.

Just a recommendation. If this is your first handgun start with something else until you are proficient. Very seriously a .22 is the place to begin, graduating to .38/.357 and finally .44 Magnum or .45 Colt, before jumping into a very specialized gun like either X-Frame.