PAL discs can have a better image (higher resolution), but often that's not the case (e.g. if they're just "upgraded" from an NTSC original).
In the early days of DVD, Warner digitized the films at 625 lines (so they could produce proper PAL discs) and 'degraded' the image for NTSC (to 480 lines).
Why do you assume beforehand that the PAL version of PF could not be superior in this respect to a specific NTSC version?