Every time played will show you every time the selected song was played with information about where in the show it was played.
Show graph will give you information about the number of times each song has been played per year and what percentage of shows that was. If the text mode box is checked, you get two separate graphs, using the pre tag. When it is not checked, there is one graph created by a table.
Obviously, show both, shows both the graph and the every time played.