If you get both imbues and level them equally at a higher lvl you can donate some damage to glavie's two imbue thread and once and for all be able to see what the difference is between the imbues.
And for those saying everyone is imune to ice, I beg to differ. If no one has ice, then there is no need to be immune right? With the addition of mana shield I have seen alot of disscussion on dropping light or fire for a full ice tree in nukers. Now if that nuker no longer has fire, then they can't be immune to ice, same as bowers and spear users. So saying everyone is immune to ice is a statement that doesn't hold true.