Question: What Does HD or XL Mean in App Names?
With the debut of the iPad, a new naming scheme cropped up at the App Store and suddenly some apps had the labels "HD" or "XL" at the end of their names.
Answer:
Those labels are used to differentiate native iPad apps from apps that were designed to run on the iPhone and iPod touch.
Native iPad apps run at a higher screen resolution than other apps due to the iPad's larger screen size. The iPad can run apps designed for the iPhone's relatively small screen, but to do so it either has to run them in a small window or perform a trick to scale them up to full size.
HD and XL (presumably standing for "high definition" and "extra large", though there hasn't been official word on that) indicate that the apps were written for the iPad's screen and that they don't need to be scaled up to fill the entire screen.
