Polarization force: the ability to cause other molecules to deform, which is related to the charge density. The higher the charge density, the stronger the polarization force.
HBr is more polarized than HI.
Polarizability: Self-deformation ability, which is influenced by many factors, including charge, radius, electronic configuration, etc. Here, the radius affects.
The deformability of HBr is obviously not as good as that of HI, that is, the latter has higher polarization.