These transitions are not intuitive, so it not easy to explain. Simply, if you know the Bloch theorem well as a basis to describe approximately the solutions in a periodic system, you can understand that this theorem is based on a local periodic potential. Normally a Bloch state lead to the band theory where a partially occupied band is a conductor (there are delocalized states) and fully occupied bands is an insulator or a semiconductor (localized state).
Now the problem is the fact that the potential in solids is not a local periodic potential.
When the non-local electron-electron (e-e) interactions are dominant, the Bloch state is disturbed $\rightarrow $ We have a Mott transition the material with a partially occupied band become an insulator. When the potential is not strictly periodic, due to impurities (even if the e-e interaction can be neglected) the Bloch state is also disturbed $\rightarrow $ we have an Anderson transition.
For Bloch's theorem to remain valid, the electrons should have enough kinetic energy compared to the quantities affecting the periodicity of the potential (e-e interaction or impurities). Therefore a wide bandwidth $B$ (or hopping integral) is needed as in your image compared to $U$ or $W$ affecting the potential.