difference between presentViewController and UINavigationController?

Question

Please tell the difference between presentViewController and UiNavigationController? Could I use presentViewController instead of

Answer 1

The UINavigationController maintains a navigation stack for you. You are then able to navigate through hierarchical content.

http://developer.apple.com/library/ios/#documentation/uikit/reference/UINavigationController_Class/Reference/Reference.html

If you use UIViewControllers presentViewController method you are basically just replacing the view controller. no navigation stack is maintained for you.