iPad and iPhone have some difference, I have summarized that in below:
iPad and iPhone use the same SDK to develop, and iPad have not all the feature of iPhone. eg, Call, send SMS, iPad1 have no camera. So iPad can't use these features that hardware limited in development.
And there are only a little difference in the development between iPad and iPhone. Apple have some UIKit only support for iPad, because it's bigger screen. For example:
1. UISplitViewController. It's a container view controller that manages the presentation of two side-by-side view controllers. Detail see reference: B
2. UIPopoverController. It is used to manage the presentation of content in a popover.Detail see reference: B
3. Window presentation style. In iPhone app, Modally presented views always cover the visible portion of the window, but on the iPad, view controllers use the value in their modalPresentationStyle property to determine appearance when presented modally.Detail see reference: C
Because the screen bigger than iphone, so on the iPad UI design, these is a pop up Model view concept.
Except above, And others are the same in development.