  Physical properties of multi-orbital materials depend not only on the
strength of the effective interactions among the valence electrons but also on
their type. Strong correlations are caused by either Mott physics that captures
the Coulomb repulsion among charges, or Hund physics that aligns the spins in
different orbitals. We identify four energy scales marking the onset and the
completion of screening in orbital and spin channels. The differences in these
scales, which are manifest in the temperature dependence of the local spectrum
and of the charge, spin and orbital susceptibilities, provide clear signatures
distinguishing Mott and Hund physics. We illustrate these concepts with
realistic studies of two archetypal strongly correlated materials, and
corroborate the generality of our conclusions with a model Hamiltonian study.
