Yes this comparison is just present because warg-riders are the counter part of Rohirrim. However i suppose DieWalkure meant the specific comparison between only Archers: on one hand we have the well-trained Rohirrim archers, on the other the warg-archers which are more a "wild version" so the opposite.
Right. They are the exact nemesis (evil counterpart, to be more precise) of Rohan's horse-archers, as Orcs are the violent and marred version of the Elves. This is exactly what I wanted to point out