The diference between above/over and below/under.

Above / over :
 

• Above : If one thing is above  another one, it is directly over it or higher  it.
• Over :    one thing is over another thing  

Below / under :

• Below :  something is below something else, it is in a lower position.
• Under:  a person or a thing is under something, they are at a lower level than that thing, and may be covered or hidden by it.