Why are my Unrealized Profit and Realized Profit different?

The prices listed on the portfolio show the estimated world price based on mid-price. So the unrealized profit shown on the portfolio page is only an estimate and will likely show a different price when the transaction execution is carried out.

This happens because there is a possibility of slippage when the execution is executed, because the execution price is very dependent on the order book depth, volatility factors and others. To reduce the possibility of slippage, users are advised to use limit orders and not market orders.