What Is the Difference between Front-Running on a CEX versus a DEX?

On a Centralized Exchange (CEX), front-running is typically done by an exchange employee or a high-frequency trader with privileged information about the order book. On a Decentralized Exchange (DEX), front-running is often executed by miners or validators (known as Miner Extractable Value or MEV) who see pending transactions and place their own transaction with a higher gas fee to execute first.

CEX front-running is regulatory/insider risk; DEX front-running is protocol/MEV risk.