For the Home button and back button
I have been testing the program in HTC's EVO.
(EVO may be the name of Japan only)
Home button and back button, the movement is entirely different, in a program.
(In the case of my smartphone)
In Android, The Home seems to be a home app.
Therefore, in my Android, If I press the Home button while moving an app, the app remains in the memory, and the home start.
Back button prepare the erasing of memory when compared with home.
When you press the Back button while moving an app, you will exit the app you are running.
(The current state of the data will disappear)
In the program, Back button to boot up until onDestry(), Home just start onPouse(), and it seems only to change the screen.