iPhone maps question

There are two icons in the upper right corner. Top one is settings. Just below it is a little pointer. Default seems to be an outline of the pointer at a 45° angle. Tap it and the pointer turns solid. Tap it again, and it becomes solid pointing straight up. I can’t find an explanation of these modes and their function.

In normal scrolling around operation the arrow is an outline, when you tap the arrow, it becomes solid blue and the map is then centered on your location. When the icon is solid and pointing up, the map will reorient according to which way the compass thinks you’re facing.