What is the difference between getIntent() and getting intent from savedInstanceState?

Hi all I'm trying out the android passing of intents between 2 classes and I've realized there are 2 methods to passing intents ,

The first is using getIntent method here:

Bundle extras = getIntent().getExtras();
mRowId = (extras != null) ? extras.getLong(DrugsDbAdapter.KEY_ROWID) : null;

And the second method is accessing the savedInstanceState:

mRowId = (savedInstanceState != null) savedInstanceState.getLong(DrugsDbAdapter.KEY_ROWID) : null;

In both methods I'm trying to access the RowId which I can then use to fetchData. Whats the difference between both methods ? Which one is better ?