High angle shot - This shot can be used for various reasons. It can be used to show somebodies perspective. It may also be to show how over powering the other character is compared to the character on screen.
Low angle shot - This shot may also be to show somebodies perspective. It also helps show the audience the contrast of size of the person and the building/object. The example above gives us the impression that the building is much taller and overpowering than the person looking at it.
Level/Neutral - This shot has no real purpose, other than to give the viewer a clear shot of what is going on.
Tilted - This shot is used to confuse the audience, as we are used to looking straight at something, and not at something at an angle. The example above gives us the impression that the view we are seeing, is from something that has just been dumped on the side.