Tapered vs straight diff axles

Hi all. I am asking if anyone knows if there is any differences in the two types of axle shafts used in a Borg Warner diffs in early model Valiants. I have seen tapered shape where the shaft taperes from large diameter at the hub end to the smaller diameter at the spline end. And the other type of axle shaft is the same diameter from hub all the way to just before the splines where it is machined down to the spline diameter. The straight shaft looks square as the tapered looks conical. Does anyone know which one would be stronger? They both take the same sealed ball bearing.
Regards
Billy d...