This looks confusing but is actually quite simple.
Native SDK is the underlying platform for both options. You simply write C++ application. Hovewer if you go just with Native you have to write your own presentation in C++ which #1) is not that easy and #2) will not guarantee your app has native look and feel.
For this reason RIM introduced Cascades framework. Its really a framework on top of C++ native SDK. It uses QT under the hood but provides BlackBerry specific UI controls which give you native BlackBerry experience.
Cascades includes QML (declarative method for constructing UI - sort of like HTML just on steroids) with ability to run JavaScript code and integration with your C++ application. You can construct QML elements from C++ or you can create QML elements in QML and access them from C++. Also from QML you can call C++ functions and use C++ objects.
You can develop an app only in QML without writing line of code in C++ (the main function will still be there and it is still technically C++ application, you just dont need to write any C++ code- all presentation and logic is in QML) or you can develop an app using C++ and declaring all QML elements in C++ without writing single QML line.
Most likely you will do both (most screens will be in QML with some in C++ with most business logic in C++)
Hope this helps
---
If you find my post helpful please "like" it and "accept as a solution"
