They're pretty much the same thing.
-First off, the so-called 'technology' in science fiction is rarely based on any real science, it's pretty much magic already anyway.
-Second, both genres require a "straight man", someone who's either a foreigner, or simply so out of touch that everything needs to be explained to them, otherwise the author has no excuse to weave in exposition, even if it's not obvious, if you aren't completely lost, it's there.
-Third, kingdoms and planets are pretty much the same thing, just with a different look, in fact right off the top of my head, I can name 3 fantasy works(Chronicals of Spellborn, Allods online, and Lusternia where people use magic spaceships to travel between different worlds, making two conventions that were already more or less the same thing somehow even more similar.
Really the only reason why people think they're two different things is because the science fiction works that are actually both original and good become more well known than their fantasy equivalants, while the many, many uninspired, mediocre works remain obscure, giving the impression that science fiction is more creative or progressive or whatever.