This is the main difference between the two platforms. When comparing, consider not only the set of financial instruments but also other parameters that are suitable for you. For example, MT5 contains an economic calendar that allows you to track financial events and supports pending orders, including Limit and Sell Stop, Buy Limit, and Stop Limit, Buy Stop and Sell Stop Limit.
Netting. MT5 supports a system that allows you to have only one open position at a time for one financial instrument, while there are no such restrictions for the second platform. So, new open orders for one financial instrument are combined into one position and averaged.
The number of financial instruments. In MetaTrader 5, there is not only a wider selection of financial instruments but also more trading indicators, scripts and expert advisors. It has 21 timeframes, and MT4 has 9 only.
The number of time frames. Expanded selection of time frames allows traders and investors to track market dynamics more precisely.
Depth of market. MT5, unlike MT4, reflects the depth of the market and expands the opportunities for hedging assets.
Economic calendar. In MetaTrader 5, comprehensive information on the stock market is published, including quote prices, events, company data, and much more. For example, international reports on various indices and other events on the economic calendar are published every day.
Programming languages. Metatrader 4 uses MQL4 and Metatrader 5 uses MQL5. Scripts and indicators written in MQL4 will be incompatible with MT5 and vice versa.
Email. Both versions of the program have a chat for traders and a mail service, but MT5 has the ability to attach files when sending emails.
MT5 also has an option to partially fill an order when a trade is executed with the maximum lot volume currently available for trading on the market, and you can also set additional execution conditions for the order. The MT4 platform only supports Fill or Kill orders. This means that the order can be only cancelled or fully performed.