coordinate system confusion

Hello,

I have a 3D time-dependent diffusion model that I have built. This is a cylinderical geometry with diffusion of a substance taking place from the center of the cylinder to the outside. I tried using both the default coordinate system ("global coordinate system") and inputting cylindrical coordinates, and asking COMSOL to solve using the "cylinderical coordinate system". However after solving, both solutions (concentration profiles) look the same, so I am curious why that is? Is the default coordinate system decided by COMSOL, or is it automatically the cartesian system? If so, shouldn't the cartesian coordinate system generate different results?

Thanks,
Vaishnavi