Why different results with same prices?

 

Why (with metatrader 4) an order opened at the open of a candle and closed at the open of the next, and at the same identical prices, in the tester gives a loss of 0.4$ and in real account 0.44$; and also profits in real are lower and in the tester higher. How is it possible, what is the reason of this difference? opening and closing prices of the order are the same in the tester and in real...