The answer to 'difference between backflow preventer' is that a backflow preventer is a plumbing device that prevents the reverse flow of water or other liquids, gases, or solids into the potable water supply. There are several different types of backflow preventers, each designed for specific applications and with varying levels of protection.
The main types of backflow preventers are: reduced pressure zone (RPZ) assemblies, double check valve assemblies, and atmospheric vacuum breakers. RPZ assemblies provide the highest level of protection, while atmospheric vacuum breakers offer a basic level of protection for low-hazard situations. The choice of backflow preventer depends on the degree of hazard, water pressure, and installation requirements of the specific application.