My interpretation, which is demonstrated in this journal, is that design research is concerned with issues in which the end result is the creation of a service or object that has somebody using it. And so there are various techniques that you can perform that can help figure out what the physical porperties are of the resulting service or object, and in my opinion, the data gathered for design research is more focused what exactly is going to be in that service or object.
Marketing research gives you the group of people, or category of objects in which the end service or objects will exist.