Supermassive black holes and/or very dense stellar clusters are found in the central regions of galaxies .
Nuclear star clusters are present mainly in faint galaxies while upermassive black holes are common in galaxies with masses \geq 10 ^ { 10 } M _ { \odot } .
In the intermediate galactic mass range both types of central massive objects ( CMOs ) are found .
Here we present our collection of a huge set of nuclear star cluster and massive black hole data that enlarges significantly already existing data bases useful to investigate for correlations of their absolute magnitudes , velocity dispersions and masses with structural parameters of their host galaxies .
In particular , we directed our attention to some differences between the correlations of nuclear star clusters and massive black holes as subsets of CMOs with hosting galaxies .
In this context , the mass-velocity dispersion relation plays a relevant role because it seems the one that shows a clearer difference between the supermassive black holes and nuclear star clusters .
The M _ { MBH } - { \sigma } has a slope of 5.19 \pm 0.28 while M _ { NSC } - { \sigma } has the much smaller slope of 1.84 \pm 0.64 .
The slopes of the CMO mass- host galaxy B magnitude of the two types of CMOs are indistinguishable within the errors while that of the NSC mass-host galaxy mass relation is significantly smaller than for supermassive black holes .
Another important result is the clear depauperation of the NSC population in bright galaxy hosts , which reflects also in a clear flattening of the NSC mass vs host galaxy mass at high host masses .