The reset via the "needle hole" will simply reset the power and thereby give your unit a hard boot in case it "hangs" completely.
The factory reset will remove all app data, settings, 3rd party apps, updates of system packages, and returns the unit as if you got it from the factory.
Note: After a full firmware flash, you actually have a "new" system. So if you were on April firmware (for example) and update to October firmware and in November you do a factory reset, it will go back to the last full firmware flash, so to the October firmware without anything else.
