I hunt with 300 grain hard cast bullets. Without exceeding published loads you can get 1750 fps out of the 454 with 300 grainers. The 45 pushes them at about 1200 fps with max loads. Energy at 100 yds is about 1360 vs. 720. As Bighorn said the 454 has nearly double the energy.
You can load the 454 down to 45 levels, but you can't go the other way.
I shoot open sights and I'm not much good beyond 100 yds so the better trajectory isn't nearly as important to me. If you're shooting scoped there's a decent difference between the two. Here's the trajectory according to Hornady's calculator:
454:
50 yds: +1.3
75 yds: +1.2
150 yds: -5.6
45:
50 yds: +3.1
75 yds: +2.5
150 yds: -11.1
You'll get no arguments from me regarding the 45 Colt's ability to easily anchor any of the above mentioned game, but you can't deny that the 454 throws lead a lot faster and a little bit flatter.
