MetaTrader 5 vs MetaTrader 4: What's Actually Different

MetaTrader 4 (MT4) launched in 2005 and became the de facto standard for retail forex trading for well over a decade. MetaTrader 5 (MT5), released in 2010, was built as a genuinely new platform rather than an incremental update — and the two are not interchangeable, especially once you start automating. The most practically important difference for algorithmic traders is the programming language: MT4 uses MQL4, MT5 uses MQL5, and while they look similar on the surface, MQL5 is a proper object-oriented language closer to C++, with a materially different event model, order system, and built-in function library. An Expert Advisor written for MT4 does not run on MT5 without a real rewrite, not just a find-and-replace. MT5 also introduced a genuine order-book / depth-of-market view for supported instruments, a built-in economic calendar, native support for hedging AND netting account modes (MT4 was hedging-only), and access to a wider range of asset classes beyond forex — stocks, futures, and more, depending on what the broker enables. The strategy tester in MT5 supports multi-currency backtesting in a single pass, which MT4 never did natively. None of this makes MT5 automatically "better" for every trader — plenty of brokers and signal providers still run MT4, and its simplicity is itself a feature for some use cases. But for anyone building or running a serious automated strategy today, MT5 is the platform with the more capable execution engine, the more actively maintained language, and the clearer long-term support runway from MetaQuotes.