The distinction that is important here is, Who made the works salvific in the first place. A pelagian (or some other deistic moralist) would say that the works are independent of grace. But we say that the works are salvific because of the sacrifice of Christ and the grace that outpours.
And we would say that if the works were salvific it would disgrace the sacrifice of Christ by demeaning it as unworthy. I suppose that among all of our camps, there are many gloves left on the gym floor over this one. :)