Sci-fi uses the images that sf - starting with H.G. Wells - made familiar: space travel, aliens, galactic wars and federations, time machines, et cetera, taking them literally, not caring if they are possible or even plausible. It has no interest in or relation to real science or technology. It's fantasy in space suits. Spectacle. Wizards with lasers. Kids with ray guns. I've written both, but I have to say I respect science fiction enough that I wince when people call it sci-fi.

A panda walks into a tea room and ordered a salad and ate it. Then it pulled out a pistol, shot the man in the next table dead, and walked out. Everyone rushed after it, shouting "Stop! Stop! Why did you do that?" "Becuase I am a panda," said the panda. "That's what pandas do. If you don't believe me, look in the dictionary." So they looked in the dictionary and sure enough they found Panda: Racoon-like animal of Asia. Eats shoots and leaves.

Science fiction - and the correct shortcut is 'sf' - uses actual scientific facts or theories for the source ideas or framework of the story. It has some scientific content, however speculative. If it breaks a law of physics, it knows it's doing so and follows up the consequences. If it invents a society of aliens, it does so with some respect for and knowledge of the social sciences and what you might call social probabilities. And some of it is literarily self-aware enough to treat its metaphors as metaphors.

I went to the springs while the sun was still up, and sitting on a rocky outcrop above the cave mouth I watched the light grow reddish across the misty pools, and listened to the troubled voice of the water. After a while I moved farther up the hill, where I could hear birds singing near and far in the silence of the trees. The presence of the trees was very strong...The big oaks stood so many, so massive in their other life, in their deep, rooted silence: the awe of them came on me, the religion.

The literature of the emperor penguin is as forbidding, as inaccessible, as the frozen heart of Antarctica itself. Its beauties may be unearthly, but they are not for us.

You fear them because you fear death, and rightly: for death is terrible and must be feared,' the mage said...'And life is also a terrible thing,' Ged said, 'and must be feared and praised.

But now his dry and silent grieving for his lost wife must end, for there she stood, the fierce, recalcitrant, and fragile stranger, forever to be won again.