"As distinct from" means "consider the quality of the course and the quality of the instructor separately." Suppose that you did not like the course. Perhaps it is a course on the films of Ingmar Bergman and you discover that you hate the films of Ingmar Bergman. Nevertheless, you find that the instructor is knowledgable and does a wonderful job of presenting and explaining these films that you hate. If you were asked to assign ratings on a 1 to 5 scale, you might rate the course 2, but in evaluating the instructor, as distinct from the course, you might give the instructor a 5.

It means "considered separately from". For example, if you have a brilliant instructor who had to present crappy materials, you should not penalize them for that.