  Two very important problems regarding spreading phenomena in complex
topologies are the optimal selection of node sets either to minimize or
maximize the extent of outbreaks. Both problems are nontrivial when a small
fraction of the nodes in the network can be used to achieve the desired goal.
The minimization problem is equivalent to a structural optimization. The
"superblockers", i.e., the nodes that should be removed from the network to
minimize the size of outbreaks, are those nodes that make connected components
as small as possible. "Superspreaders" are instead the nodes such that, if
chosen as initiators, they maximize the average size of outbreaks. The identity
of superspreaders is expected to depend not just on the topology, but also on
the specific dynamics considered. Recently, it has been conjectured that the
two optimization problems might be equivalent, in the sense that superblockers
act also as superspreaders. In spite of its potential groundbreaking
importance, no empirical study has been performed to validate this conjecture.
In this paper, we perform an extensive analysis over a large set of real-world
networks to test the similarity between sets of superblockers and of
superspreaders. We show that the two optimization problems are not equivalent:
superblockers do not act as optimal spreaders.
