If you are referring to the sound of the fingers, sliding on strings, that's potentially happening with a wide range of variables....so comparing the two devices, wont help you breaking down the issue.
Usually it's a countereffect of hi gain settings, especially with bright amps/cabs, but it can be exacerbated by compressors, strings, pickup height, playing style etc etc.
Also, it can be expected when using the acoustic sim, similar to what you get with piezo saddles.
We need more info. :)