The GoGear Ariaz is the slightly smaller of the two, with it packing a 2-inch display, along with 4GB, 8GB, or 16GB of storage, an FM tuner, a built-in mic for voice recording, and a somewhat unique interface that includes a combination of "touchscreen buttons" and a large rocker key.
ENGADGET: Philips debuts GoGear Ariaz, Opus PMPs