  We perform a comparative study of the Anderson localization of light beams in
disordered layered photonic nanostructures that, in the limit of periodic layer
distribution, possess either a Dirac point or a Bragg gap in the spectrum of
the wavevectors. In particular, we demonstrate that the localization length of
the Anderson modes increases when the width of the Bragg gap decreases, such
that in the vanishingly small bandgap limit, namely when a Dirac point is
formed, even extremely high levels of disorders are unable to localize the
optical modes located near the Dirac point. A comparative analysis of the key
features of the propagation of Anderson modes formed in the Bragg gap or near
the Dirac point is also presented. Our findings could provide valuable
guidelines in assessing the influence of structural disorder on the
functionality of a broad array of optical nanodevices.
