Content strategy is concerned with the systems and processes for structuring, organising, managing and creating the content. As such it is closest to the traditional user experience professional.
Editorial strategy is then concerned with what to say and to whom. It covers messaging, themes , topics, points of view and how they are expressed. As such it is closest to the writers and search specialists.
Content marketing covers how to drive conversation around content. How to use it to attract attention, engagement and participation. And as such closer is to the traditional communication and marketing professional.
Źródło: Content Strategy: no longer just the preserve of the web professional, Johnny Holland