Copy trading connects your account to another trader's, the provider's, so that their trades are reproduced in yours. It is offered through MQL5 Signals inside MetaTrader, through broker platforms, through social trading networks, and through trade-copier software that links two terminals. The provider trades; the copier follows, scaled to their own balance by a copy ratio.
Where the results diverge
The copy arrives after the original. Even a fast copier adds a delay, and a signal service adds more, so the copier's entry is later and usually worse. The copier's broker has different spreads, symbols and fills, and the differences on the page about brokers apply in full. The copy ratio decides risk, and a provider trading at high risk on a large account produces an unsafe ratio on a small one. And the provider's strategy is unknown: the copier sees trades, not rules, and cannot tell whether the provider uses stops, holds losses, or has changed approach since last month.
Providers also have incentives the copier does not. Many earn from volume or subscriptions rather than from the copier's profit, and a provider with a dramatic recent month attracts subscribers regardless of what happens next.
Running your own EA instead
An EA you install runs on your account, at your risk setting, with rules that are described, a record you can inspect, and a stop loss on every trade if it is well built. There is no delay, no ratio, and no provider whose interests differ from yours. The costs are yours to manage, and the results are yours, including the losing months.
A provider's signal shows 90 per cent growth in a year. A copier at a different broker, with a 25 per cent copy ratio and an average delay of four seconds, receives 62 per cent of the provider's trades at usable prices, and the year ends at 11 per cent, with the provider's largest drawdown reproduced in full because the ratio scaled it faithfully. The provider's page still shows 90.
Copying makes sense for a discretionary trader you trust, trading slowly enough that delay does not matter, on a broker that matches yours. For anything systematic and frequent, owning the system is the better structure: the record you see is the record you get, the risk is the setting you chose, and the strategy does not change when someone else has a bad week. A copied EA is also an EA whose stops you cannot see. Your own EA's stops are on your chart.