Matlab sim command gives different simulation result from Simulink play button

Hi,

My Simulink model is .mdl with Matlab 2015a. The model is in Accelerator mode. I realize that when I use Simulink play button, the simulation result is different from using sim command sim('model_name.mdl'); The result is not so significant, the simulation still follows the expected behavior but the numerical difference is noticeable.

I wonder anyone experienced this and if there is a solution.

Thanks,

Dave