You asked a complicated question that can't be answered clearly. There are not only different methods of calculating "energy" but you also have to consider, overall, how that energy is delivered. There is a difference, and there is a difference between equal rounds in how it is transferred by these rounds.
If we take the 300 grain bullet both rounds according to my data move at 2,000 fps +-. and they both have energy ratings of a bit less than 3,000 foot-pounds.
So, neither one can seriously claim superiority in simple energy figures for this specific set of circumstances.
Now since we can run the .500 up to a 500 grain bullet at 1,400 fps at maximum loadings, yet the .460 can max out at 1,500 fps for a bullet that is only 395 grains. Their energy was listed as 2,250 and 2,040 foot pounds respectively.
Do we want to talk about using absolute maximum yield, or do we want to just talk in circles about the dozens of different combinations of loads, reaching from lightweights of each to maximum loads of each?
The .500 is obviously capable of much higher energy and probable performance in hunting, based on those figures. Maybe that's correct? The max factory loading that I found for .500 carries about 200 foot pounds of energy more than the .460 in the heaviest bullets in normal use. That's about as much energy of a standard loaded .380 acp. Many people would call that insignificant.
And hey, did anyone notice that the .460 in a 300 grain load has 2,826 and the .500 500 grain has only 2,250? About 400 foot pounds more. That's about the power of a 9mm luger.
Since energy levels are all that matters to a lot of people, it's obvious that a whole lot of people will argue that the .460 is a superior round. I know which one I want my alaskan guide carrying; Neither of them. I want him to be hauling a .45-70 rifle.