| X_1-X_2| \sim \left(\begin{array}{ccccccccccc}
 0 & 1 & 2 & 3 & 4 & 5 \\
\frac{6}{36} & \frac{10}{36} & \frac{8}{36} & \frac{6}{36} & \frac{4}{36} & \frac{2}{36} \\
\end{array}\right)