Both choke and pinch collars are generally made of a metal chain and acts through the tightening around a dog’s neck when a handler pulls or jerks on the leash.
A choke chain dog collar type is designed to control your dog or correct its behavior by tightening around its neck. Usually there is no way to control how much a choke chain can tighten (unless there is a limiting martingale loop), so some risk or choking your dog is possible in this case. It may also cause injuries to a dog's trachea, esophagus, the blood vessels around the eyes, neck sprains, casue a nerve damage, fainting, and temporary paralysis.
Prong collars contain metal spikes on the inner side that ‘pinch’ a dog’s neck if he pulls on the leash or if a handler jerks to stop dog's wrogn action or teaches some command. Prong collars have a martingale chain loop that controls how tightly the collar chokes, which reduces the chance for accidental injuries. If a prong collar size is chosen correctly and worn at the right place that is described above, it will not harm your dog.