The iPad app is actually an iPhone app according to Apple. The significance is in the viewing experience.
On the ipad the Pprune app appears as a small mobile phone in the centre of the screen. You can double the size by clicking on '2x' but then you lose the resolution making it unpleasant to use.
Using Pprune on safari (the Apple web browser) is far, far better. I see the full screen and have all the normal functionality.
MH152