  We report on the following consequences of the relations between non-singlet
contributions to $g_1^N$ and $F_1^N$ structure functions found within infrared
renormalon model: the discovery of new next-to-leading order inequalities
between non-singlet polarized and unpolarized parton densities, and the
existence of the effects of similarity between non-perturbative and
perturbative contributions to the unpolarized and polarized Bjorken sum rules.
