Well scarring is when you hang on the ledge, then DI away and use side B immediately after which makes Wolf appear in the middle of the stage and sweetspot some space behind him.
Semi-scarring is when Wolf uses his side B and holds down which makes Wolf miss edges completely. Wolf can use it at distance and end up on the edge of the stage, or closer, it's all in what he wants to do. If you find the right spacing for it and time it right, he can hit the edge and sweetspot an edge guarder then grab the ledge itself. It makes it possible for Wolf to have very differing recovery tactics and can be, if used correctly, very unpredictable.