Instant Execution: Instant Execution attempts to fill your order at the exact price you requested. However, if the market price moves before your order is executed, the order will not be filled at the original price. In such cases, you will receive a "requote," which is a notification informing you that the price has changed, and you will need to either accept the new price or cancel the order.
This method gives you control over the price at which the trade is executed, but it relies on the market price remaining stable long enough for the order to be processed.
Market Execution: Market Execution is executed at the best available price in the market at the moment of execution. This can occur within fractions of a second, ensuring fast execution. However, since market prices fluctuate rapidly, the price at which your order is executed may be different (either higher or lower) than the price you saw when placing the order.
This is ideal for traders who prioritize speed and efficiency over price certainty, as it guarantees the execution of the trade as soon as possible, even if the price slightly varies from the one displayed at the time of placement.