  We prove a conjecture of Nadjafi-Arani, Khodashenas and Ashrafi on the
difference between the Szeged and Wiener index of a graph. Namely, if $G$ is a
2-connected non-complete graph on $n$ vertices, then $Sz(G)-W(G)\ge 2n-6$.
Furthermore, the equality is obtained if and only if $G$ is the complete graph
$K_{n-1}$ with an extra vertex attached to either $2$ or $n-2$ vertices of
$K_{n-1}$. We apply our method to strengthen some known results on the
difference between the Szeged and Wiener index of bipartite graphs, graphs of
girth at least five, and the difference between the revised Szeged and Wiener
index. We also propose a stronger version of the aforementioned conjecture.
