With modern cases, the .45 Colt can be loaded to equal the .44 Magnum in power, give or take a few foot pounds. But the .45 Colt is chambered in a lot of old and weak guns, so factory loads must be kept to low pressures.
One guy I knew loaded two .45 Colt loads, one for his Ruger and one for his old Colt SAs. He got mixed up and blew the cylinder on a first generation, 4 digit serial number. One unhappy camper.
Jim