Is there any difference between using LRAC and LRATC in a long-run market structure diagram? I am currently being taught to use average total cost (ATC) to label the U-shaped curve in the short-run on a market structure diagram, and long-run average cost (LRAC) for the equivalent curve in a long-run market structure diagram. 

Is any difference between labeling the U-shaped curve in a long-run market structure diagram long-run average total cost (LRATC) and labeling it LRAC?
It is one and the same thing. Notation might be different.