I've recently bought an Ipad and realised that all of my Iphone applications can be used on Ipad because I activated the Ipad with the same Apple ID as Iphone. All the applications on the Itune were loaded automatically into Ipad, although they appear to be very small, but I can enlarge them two times. I wonder whether Ipad application, or application that made only for Ipad can also be used on Iphone? Thanks in advance.