Polygon P.O.S. And ZK EVM

ZK EVM should be more secure because it derives security fully from Ethereum, assuming the cryptography and the math of ZK EVM is correct. So there are these differences in trust assumptions and significant differences in fees. It's mainly applications that are looking for maybe lower fees, higher throughput, and are not security first. For example, some Web-free games and stuff like that might still use P.O.S. chain.