Welcome! If you do a search, you will find questions just like yours with tons of discussion and answers. It boils down to this: If you are hunting with a rifle, it must be chambered for a round less than 1.6" long-which is mostly pistol calibers-AND the bullet must be .357" or bigger. So a .44mag out of a rifle-good. A 30-06 out of a rifle-illegal.
If you are hunting with a pistol, it must fire a bullet at least .243" in diameter, but there is no maximum length. So .44mag out of a pistol-good. 30-06 out of a pistol-good. 460 weatherby out of a pistol-fine.
And don't worry, it isn't supposed to make sense. It's comes down to us from those who know best.