Actually, one big difference between fantasy and Sci Fi is that Sci Fi tends to ignore religion as much as possible. Fantasy tends to have some sort of fictional religion as a fairly integral part of the story and setting as well as addressing other topics (like magic) that are sensitive to people of religious faith. Sci fi, on the other hand, tends to avoid these issues as much as possible, though there are exceptions. Even when sci fi addresses these issues, it tends to be as ambiguous as possible. Many stories substitute philosophies for religions, as is the case with Star Wars. If actual religious faiths besides judeo-christian ones are used, writers tend to tiptoe around the subject of whether there is any truth to them at all. In effect, sci fi leaves a lot of room for people of faith to enjoy the stories through the filter of their own beliefs where fantasy, specifically D&D derived fantasy, doesn't.