Hi Emre,
Every prop firm and every broker will give different results because the historical data for each prop firm or broker is slightly different. This causes the Expert Advisors to take trades differently.
The FTMO Expert Advisors / robots where generated with FTMO historical data. As a result the robots should perform best when used with FTMO prop firm. Now robots can be used with different prop firms but the results will be different. So what do you do to gain confidence. To resolve this difference it is recommended to backtest with the prop firm you plan on using for your challenge and then use the results to make trading decisions.
Alan,