Because its newer, it has some of the cooler 'Sweet' sounds in the more expensive models.
"504 AWM voices, including Sweet and Cool (GM and XG Lite compatible) - digitally recorded instruments"
My keyboard is XG compatable, but for that price, you can't go wrong, and those instruments seem of better quality to mine.
Recorder seems the same to mine, but yours has a USB host, while mine only has a floppy drive making converting songs over harder.
Plus, has 5 layers for recording a song, and unlike mine, you can change the volumes of each layer after recording