What is exact difference between gravity and layout_gravity [duplicate]

Answer 1

1. Yes, your understanding is correct. Any layout_ attribute gives instructions to the parent view.
2. Generally, if a view is taking up the full width/height of its' parent, then you won't need to specify layout_gravity, you'll probably find gravity more useful. If your view does not take up an entire dimension of its' parent, you might want to align it depending on your desired look.