Change in size: Since this is the major component of both devices, it seems right to look at this measurement first. The DSi XL is 160% larger in total volume than its predecessor, with 93% more screen space. The iPad's 9.7 inch, 4:3 screen is 799.8% larger in area than the iPhone or iPod Touch's 3.5 inch, 1.5:1 screen, and its body, at 35.7 cubic inches, is 598.2% the size of an iPhone 3GS.
Colors: The Japanese DSi LL is available in Wine Red, Dark Brown, and Natural White. The iPad is available in black, with a brushed aluminum back.
Compatibility: The iPad is compatible with all iPhone apps that don't use the camera. The DSi XL is compatible with exactly the same programs as the DSi, and all DS games that don't use the Game Boy Advance slot.
New software: iLife productivity apps will be available for the iPad. No software is made especially for DSi XL.
New accessories: The DSi XL comes with a big, pen-sized stylus. The iPad is compatible with a (separate) dock that adds a full keyboard.
Announcement spin: Here's where it gets a bit eerie. Following the announcement of the DSi XL, Nintendo president Satoru Iwata said that the XL offered "an improved view angle on the screens to make it the first portable system that can be enjoyed with people surrounding the gamer," enabling a "new play style where those who are surrounding the game player can also join in one way or the other to the game play." In a promotional video on Apple's site, Bob Mansfield, Senior VIce President of Hardware, says that the IPS display offers "not only a great experience looking directly at the device, but also off-angle when you're sharing the device with someone else."
What do we learn from comparing the iPad to the DSi XL? Not much, really. But it's really weird that the latest hardware iterations from Nintendo and Apple are both oversized versions of things that we already have, isn't it?