What is a "very big difference!", chipmonks? Is the pitch is constantly higher and sped up or does it vary? If the pitch and speed is slightly higher, that is classic example of playing back a 44.1kHz sample rate file @ 48k. Is the sample rate in VP's 'project properties' set the same as the files in the timeline (though VP does not usually have problems with different rates)
Otherwise your playback device (or soundcard) could be locked to PB at higher sample rate than what the file is.
In any case, the Smooth/Enhance process does not affect pitch.