ECN & STP brokers offer you direct access to the live market by matching your orders against the other participants in the Forex market.
ECN brokers directly link you to the interbank market participants via their liquidity providers. This is unlike market maker brokers – which create the virtual market & match the traders via their internal order books or take position opposite your trade.
With transparent True ECN brokers there is no conflict of interest & generally the trading fees is also much lower. But, there may be a conflict of interest with market makers as they may be taking position against you, which means that with some broker that follow bad practices, it may be in their benefit that you lose.