The regular Polygon functions as a sidechain to Ethereum, using a Proof of Stake (PoS) consensus algorithm and Plasma chains. This design improves transaction speed compared to Ethereum’s mainnet and significantly reduces fees. However, it’s not entirely equivalent to Ethereum’s mainnet.
On the other hand, Polygon zkEVM is a zero-knowledge scaling solution fully equivalent to Ethereum. It is equivalent to the Ethereum Virtual Machine (EVM), and most existing smart contracts, developer tools, and wallets work seamlessly. The zkEVM uses zero-knowledge proofs (ZK proofs) to reduce transaction costs and significantly increase throughput.
Therefore, these are different chains with different characteristics and functionalities.