Agreed. "Self defense" can cover a lot of territory. Personally I wouldn't recommend popping a grizzly bear in the a&& with either round as you might get a lesson in "wildlife management".
On the other hand, if the potential target is likely to be an unarmored human being I think either round would serve you well. Most self defense loads these days are loaded with low flash powder and are less likely to cause a blinding muzzle flash in the dark but muzzle blast and recoil will always be harder to handle in the magnums. If you are forced to fire a magnum revolver without hearing protection - especially inside a building - the muzzle blast can be disorienting. Non magnum rounds will be a little easier to take but even those can deprive you of any real sense of hearing for an extended period. Not an insignificant factor if you are facing more than one opponent.
Out in the woods with the chance of running across a bear or a wolf or even a rabid skunk I usually opt for the .357 magnum or a .45 ACP +P or Auto Rim +P but around the house or in the car I'm generally content with a .38 Special or a standard pressure .45 ACP.