When converting from NTSC to PAL, two things need to be accomplished. 480 lines of resolution have to be upconverted to 576 lines of resolution, and 30 images per second have to be downconverted to 25 images per second
The resolution upconversion does not actually add any real picture information to the image, as you cannot create real picture information where none existed before. It does, however, make the picture viewable on a PAL display, and often results in a superficially better-looking image
The frame rate conversion actually results in a loss of temporal resolution, as PAL has a lower frame rate than NTSC