I personally think its different realms in the sense that there are peculiarities that are only present in one substance and not the other, in terms of feelings, thoughts, visions, insights and so on.. I explored more of this in some other thread, noting the difference between the realms and experiences in different psychedelics.. maybe I find it and will copy the quote here later..
In any case, of course in the end we could say ´its all one´, its all the same realm from a broader perspective.. maybe the concept of ´triangulation´ fits here, in the sense that each substance allows you to see what we could say is One reality, but from different perspectives