Earlier quoted context omitted.
Good to know. I tried "the left hand of darkness" and didn't like it. Somehow it read more like mediocre fantasy than scifi.
Because the science part takes a backseat to the cultural exploration. I guess that could be either fantasy or science fiction, but since it has spaceships it must be the latter.
My observation is that most sci-fi is set in a world mostly similar to ours, except for one aspect/tech that's dialed to 11. Fantasy has a much looser attachment to our world, and sometimes the weirder, the better. Also, each has its own genre-tropes that can be used (or subverted) but barely translate to the other - I'm yet to see a fantasy story that is grounded in egalitarianism.