The comparison of the structural and magnetic properties of molecular nanomagnets (MNM) and magnetic nanoparticles (MNP) can be instructive to get a deeper understanding of the magnetic behavior on the intermediate scale between molecular and bulk objects. In this respect iron oxo based clusters are particularly interesting, since they provide an increasing number of molecular systems with sizes close to that of iron oxide MNP. In this Minireview we report a survey of literature data aimed at improving our understanding of the emergence of MNP properties from MNM ones.