There are really two categories here. One is cartridges that can be fired in a gun marked for another caliber because the latter is simply an elongation of the former. That applies to .32 S&W in a .327 chamber, or a .38 Special in a .357 Magnum chamber. Usually, the reverse is not true and, even if possible, may well be dangerous.
The other category is that of cartridges that can fire in another caliber chamber but were never meant to do so, like .380 ACP in a 9mm Luger chamber or the .45 Colt in a .410 shotgun. Sometimes a short round will fire only if held by the extractor or the firing pin has a very long reach. This type of combination can be dangerous, especially when rifle pressures are involved. Even at best, swelled or stuck cases and malfunctions are the norm.
I suppose I might add a third category, where the two cartridges are actually the same, differing only in name, like the .30 WCF and the .30-30, the .30 Army and the .30-40 Krag, the 9mm Largo and the 9mm Bergman-Bayard, the .38 Colt Special and the .38 S&W Special.
Jim