I don't know what you mean by "... there really isn't THAT much of a difference between a .380 acp and a .45 acp." Of course there are differences, or everyone would be carrying .380s, like you do. And no one would dispute the notion that handgun rounds compared to rifle or shotgun rounds are inferior in terms of "stopping power" but this is a handgun forum, with a thread asking about which carried handgun people trust most to defend themselves with.
Are you seriously making the argument that, for instance, a .380 acp is the equivalent to a .357 Magnum, stoked with 125 grain, hollow point bullets, in terms of the only relevant criteria in terms of self-defense, "stopping power"? Seriously?