To expand on Wesshoot's answer, many of today's handgun cartridges are modifications of earlier rounds, some stretching back 100 years or more, done by keeping the same nominal cartridge and bullet dimensions, but lengthening the case to allow for more powder capacity, and hence higher velocity and more power.
Since all dimensions other than case length are equal, the older, shorter rounds can fit into chambers for the newer, more powerful rounds.
Note that this is normally only possible with straight-walled, rimmed cases. In a rimmed case, headspacing, or orientation of the case on firing, is done by the rim, and not by a shoulder or case mouth -- in essence, case length is no longer a critical factor.
So, with revolver rounds, there's quite a bit of case interchangibility.
For instance, if you have a handgun chambered for the .357 Maximum, you can fire in it .357 Magnum, .38 Special, .38 Long Colt, and .38 Short Colt rounds.
That is also a rough chronology of the development of those rounds, as well, with the .357 Max. being the newest (1980s), and going backwards in time -- .357 Mag., 1935, .38 Special, about 1898, .38 Long Colt and .38 Short Colt, both in the 1870s. A spread of about 110 years between rounds.
The same is true for the .44 Magnum (1950s), .44 Spl. (1907), and .44 Russian (1873+-).