In many ways, Open Knowledge is just a subset of Knowledge Management. While KM often focuses on internal knowledge sharing, it doesn't have to exclude externally-focused knowledge sharing, uptake, and re-use.
In the March/April 2016 issue of Online Searcher, Abby Clobridge (Founder & Consultant at FireOak Strategies) looks at 5 areas where Open Knowledge and Knowledge Management intersect and diverge:
Security and Privacy
Culture and Culture Change