Beginner's Guide to Adobe Flash/Symbols/Graphic
Graphic Symbols are the most basic of the three symbols and are mainly for static images, but one can use animation in a Graphic Symbol, but Flash will ignore any sounds or actions inside it. They also do not play independently of the main timeline, this requires an allocated frame on the main timeline.
When should you use a Graphic Symbol?
Because shapes drawn on the stage are rendered in each frame of the Flash player, sometimes they take up more resources and processor cycles than are necessary. Using an instance of a Graphic Symbol, because it is a copy of a symbol in the library, will take up fewer resources because in each frame, the Flash player refers back to the original and makes the necessary changes.