In the same brand, the external dimensions are identical. Across brands, there may be a slight difference, but none that you'd ever notice.
They burn hotter and longer, and they have a thicker cup. It does mean they can be harder for a handgun's hammer hit to set them off, but the design is such that they have the ability to contain more pressure. Some factory handgun ammo is loaded with small rifle primers right from the OEM source (.327 Federal Magnum is an example) simply to guard against leakage or bursting to contain the high pressures. (.327 Federal runs a 45k max psi)
Anyone tried small rifle in small pistol applications.
Many folks use them exclusively, some of them ran out of small pistol during that last component squeeze in 2009 and some of those guys never went back to using small pistol.