Centerfire ammunition is primed by the firing pin hitting center of the cartridge and rimfire is primed by the offset pin hitting the outter rim of the cartridge

Rimfire: the firing pin hits the RIM of the cartridge. Centerfire: the firing pin hits the center of the cartridge. Centerfire is deemed to be a lot more reliable. Rimfire less but is so much cheaper in price.

Each firearm will fire the ammunition for which it was designed. The two are not interchangeable. The location of the firing pin in centerfire firearms is different (hits the center of the cartridge, where the primer is located) and the rimfire hits the edge (rim) of the cartridge - which is where the rimfire primer is located.

in centerfire ammo the primer is in the center of the brass case it is replaceable for reloading (refilling and reusing the case) in a rim fire the primer is in the outer rim of the case It is not (easily) replaceable and you do not reload the rimfire brass guns will shoot one or the other because the gun has to be set up for the firing pin to hit the primer (center for centerfire and the outer rim for rimfire)

David, here is a quick video tutorial Sir : youtube.com/watch?v=Yq_M9nN8224

in centerfire ammo the primer is in the center of the brass case it is replaceable for reloading (refilling and reusing the case) in a rim fire the primer is in the outer rim of the case It is not (easily) replaceable and you do not reload the rimfire brass guns will shoot one or the other because the gun has to be set up for the firing pin to hit the primer (center for centerfire and the outer rim for rimfire)