What Is the Difference between a Miner and a Validator in Transaction Ordering?

In Proof-of-Work (PoW) systems (like pre-Merge Ethereum), the "miner" performs computational work to solve a puzzle and propose the next block, earning the right to order the transactions within it. In Proof-of-Stake (PoS) systems (like current Ethereum), the "validator" is selected based on their staked assets to propose and attest to the next block, giving them the authority to order transactions.

Both roles, miner and validator, are essentially the "block proposer" who controls the transaction ordering and can thus extract MEV.