MetaTrader 4 is long-established and widely used for forex CFDs, with a large library of indicators and Expert Advisors built in MQL4. MetaTrader 5 is newer and adds more timeframes and order types, an integrated economic calendar, depth-of-market and broader asset coverage, using MQL5. MT5 is not simply an upgraded MT4 — the two are separate platforms, so the practical choice often comes down to the instruments traded, the tools or EAs relied on, and which platform the chosen broker supports.