The ROC curve for two distributions $F$ and $G$ can be defined as
$$\mbox{ROC}(u) = {F}(G^{-1}(u)),$$ for $u \in (0,1)$. So, if $F=G$, then $\mbox{ROC}(u) = u$. Can I use this property to compare the two distributions $F$ and $G$? For example, by checking deviations from the identity function?