"persistent state" vs. "current state"

Attempting to decide (for my application) what to save in onPause() and what to save in onSaveInstanceState(), I combed the entire SO for hints and clear guidelines.

If I understand correctly, onSaveInstanceState() is best for saving "runtime changes" or "current state" (whatever that means), while onPause() is best for saving "persistent state" (whatever that means).

I am still having difficulty deciding what in my application constitutes "persistent state" vs. "current state". For example, while user preferences are clearly persistent, do I need to save them in onPause() when they are always saved automatically by the Android UI framework when the user changes them?

Do class data members need to be saved in onSaveInstanceState()? Do I need to do that for every class in my application?

I am confused.

Can you bring real-world examples of what must be saved in onPause() and what must be saved in onSaveInstanceState()? Except for device configuration changes, that is.

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Some new insights, after my question has been answered:

• onSaveInstanceState's Bundle is not written to anything, and it's not persistent in any way.
• onSaveInstanceState's Bundle data will only be held in memory until the application is closed.