What is the difference between a 22lr and a 223?

Answer 1

A world of difference. .22 Long Rifle is a low velocity, rimfire round. When a .22 LR round strikes a target, damage caused by the round will be limited to the crush cavity (damage caused by the round itself).

The .223, although having a projectile with the same diameter, is a much different cartridge. It's a high velocity centrefire cartridge, with a much heavier spitzer type projectile moving at a much higher velocity. Damage caused by this cartridge also includes hydrostatic pressure, which is caused by air displacement around the projectile.