Also ignoring the traditional pointed 45 Colt bullet which did little damage unlike a swc or hp.
There is a good article here:
http://www.americanrifleman.org/articles/handgun-stopping-power/
It boils down pretty simply: Would you rather be shot in the thigh with a 45 or in the head with a 38? If you go deer hunting, would you prefer to take a shot at a deer in the gut with a 44, or in the lungs with a .270?
The FBI manual points out that even if you shoot someone in the heart with a 44 magnum (or 45 Colt), there will be enough residual blood pressure in the brain to allow a determined attacker to function for 10-30 seconds. If someone is determined enough, you can shoot them in the heart and they can still live long enough to empty a 15 round magazine in you!