What’s the difference between ECN and STP brokers in Forex Trading?

ECN brokers typically charge a fixed commission while STP brokers make their money from applying a markup to the spread offered by their liquidity provider. While STP providers pass orders directly to their liquidity providers, ECNs have their own system where all their liquidity providers, traders, and other clients can trade against each other. True ECNs can show their clients the DOM (depth of market) so that their clients can see liquidity in real-time.