a UIPadding basic makes it so something is a certain distance away from the side of the UI, which a lot of pro UI designers will use that way they can maintain proper spacing of elements.
Other than that fact, UIPadding is again, and instance, so you can add it by pressing the + button on the selected object and insert it like that (its the same as creating a part or a frame, or textbutton) the method you have used does in fact work, but using a UIPadding means you dont have to have an extra button and what not, and may come in handy when programming the UI.
