Metatrader 4 backtesting uses prices that are randomly generated from bar data. By a process of interpolation, it uses the bar price data together with the tick count to generate the prices for each bar so that they start at the bar open price, touch the bar high and low, ending at the close price. If a position has both its SL and its TP within a bar's price range, it's a coin toss whether it will hit stop/loss or take profit. With the Tick Data Suite, actual price ticks are used. Nothing is left to chance - your backtests will use the prices that were historically traded and recorded tick by tick, oftentimes more than once per second.
