The 1911 is manufactured in many different calibers, by most serious mfg's. .38 super, 9x23, 9x18, .40, .45 .357SIG, .10mm and to a lesser degree, or, are available in .45 gap, .38 etc to infinity.
The choice of the caliber is dependent upon the carrier and the mindset.
.45 is slower and a bigger hole, some would argue more shock.
.40 is about the same without the same recoil though I prefer the recoil of the .45 & .357 Sig over the .40.
The .38 Super is faster and flatter as is the 9x23 but flash and recoil is softer.
Some would argue the 9x23 is the best overall carry caliber others have their own thoughts.
Buy one of each, you will sooner or later.
Blessings