Android apps scale up gracefully to any size due to the way they are made.
iOS apps have to be custom made to each device specifically, so unless there is an iPad app it will be small on screen or really large with scaled bitmap graphics.
Hardly gracefully. 'Stretched-UI' is great for resizing an app to a similar size screen that it was designed to run on, but it creates an un-engaging user experience when scaled up to larger screen sizes such as tablets as the content on the screen just ends up being spread out with a lot of wasted space on the screen.
That's why Google recommend that Android apps have a specific user interface designed for tablets and not using stretched-UI as a solution to tablet UIs.
The screenshots posted suncity are a good example of the difference between a stretched smartphone app running on a tablet and an app with a tablet specific UI.