what is the different between window based project and view based project in iPhone?

They seems pretty similar.What is the differ开发者_如何学编程ent? If I choose wrong, can I change it after I start coding?

A window-based project provides you with just a window and an application delegate class. The View-based gives you both of those, plus an initial UIViewController-based class. You can always add a viewcontroller to a window-based project, or remove it from the view-based one. If you're just starting out, I'd recommend at LEAST the view-based one.