Re: versatility of .22 Ammo- Yes, there are several different rounds that will work. Howver, as the man said, 5.56 is not one of them.
The .22 LR is a RIMFIRE cartridge. Firing pin pinches the rim against the chamber wall. 5.56 is not only a much larger bottlenecked case, but is a centerfire- firing pin strikes a primer located at center of rear of cartridge.
Within the .22 rimfire family, there is the .22 Short, and .22 LR (the .22 Long is pretty much obsolete) There are also 22 BB cabs and CB caps- very low power, very quiet. There are also .22 shot cartridges, but of very limited range and effectiveness. (large roaches at 20 ft) the .22 Magnum does NOT interchange with other common .22s.
A semi auto rifle will likely not cycle any ammo but what it was made for- commonly .22 Long Rifle- othe rounds may be fed by hand. A .22 bolt action will pretty well eat whatever you put in it. There ARE exceptions- Remington made a series of .22 autos that seems to digest anything that fits in the chamber.
One of my .22 bolt guns is a WW II Mossberg 44US target rifle. With the right ammo, if I do my part, it will put 5 bullets in one slightly ragged hole at 100 meters. I LIKE that! PS- disregard the photo- wrong picture-