What is the difference between Science Fiction and Fantasy?

Science fiction incorporates actual science to varying degrees (as of the point of its creation) into its core mechanics and concepts.
Fantasy disregards science and even uses concepts that contradict it.
Compare Star Trek’s Warp Drive to Magic or The Force. The first one is based on actual physics, the latter two are not.

SciFi for me tries to use plausable science to guess a future. Fantasy has magic and many things happening that are outside of the laws of nature. I love scifi, I don’t like fantasy.

Science Fiction is a creation of a world or universe based on extrapolation and extension of scientific solutions to present problems, like light speed and time travel.

Fantasy has to do with “magical” places and creatures, such as fairies and giants and wizards and hobbits.

Sometimes they do merge, in things like The Golden Compass.

@ragingloli So, by your reckoning, Star Wars is pure fantasy, no SciFi.

@ragingloli, @zenvelo and @JLeslie all nailed it. Star Wars is actually futuristic fantasy since it doesn’t actually use science in it’s explanation of how much of the universe works.

@filmfann
Not completely, but its core concepts certainly are.

@filmfann Star Wars is rather luke warm for me, but I love Star Trek. Harry Potter and Lord of the Rings I could not get into at all.

One problem with that explanation is that you can be so far removed from the possible science that it seems like fantasy. Perhaps 2001 would have seemed like fantasy to someone from the 1860’s, because they couldn’t fathom the idea of space travel as a possiblity.

Luke warm, haha. I get it!
@filmfann
That is why I said “as of the point of its creation”.

What about time travel stories? Science doesn’t seem to support the possiblity. Does that make it fantasy?

@filmfann
Science does in fact support time travel as a theoretical possibility.

Einstein said it couldn’t happen.

Time travel is usually scifi in my opinion. Of course fantasy can use time travel within the story though.

Time travel is viewed as theoretically feasible as far as science is concerned currently, but only in going forward in time.

@filmfann
Time travel backward in time is actually a possibility within Relativity.
And about Einstein; he rejected Quantum Mechanics out of ideological reasons, and in his attempts to create a grand unifying theory, he even contradicted some of his own science.
“Einstein said” is not an argument.

To me Fantasy is magical worlds like, lord or the rings type deals. People aren’t necessarily human. Dragons, fairies, trolls, vampires, werewolves, pixies, unicorns, magical happening, greek gods and so on. Basically stories that have been passed down.
Sci fi to me is everything else. Human stories mixed with cyborgs, future worlds, time travel, or traveling in space where monster exists, or mutations of humans or alternate universe, aliens. Stories that are more of this generation than past. Stories that aren’t told as being true but can possibly be true some day.

Kirk buggering Spock over the “captain’s log”

I’m not entirely certain of the criteria, I generally calls ‘em as I sees ‘em. But what @ragingloli and @zenvelo pretty much sum up how I judge it. And then there’s science fantasy, which further complicates specification.

They are closely related; both are conceived out of fiction. Not much difference at all.

I read a description of these genres once in one of the fantasy or science fiction magazines. I wish I could remember which one. It might have been Asimov’s, in which case it probably would have been written by Norman Spinrad.

Whoever wrote said that it all fits in the realm of speculative fiction. Strictly speaking, he wrote, science fiction is a subgenre of fantasy. Fantasy is all the things we can think of that are not currently possible. Science fiction are the things that are not possible but that must be scientifically plausible.

One rule I read said that hard science fiction was allowed to break one rule of physics (say time travel). The more rules of physics you break, the more you get into the realm of pure fantasy, but it is all fantasy. Just some of it seems more possible than other parts of it.

If you break no laws of physics, then I guess it is considered ordinary fiction. Although a lot of that is speculative, if it happens in the near future. But you can also have speculation about things that happened in the past, so you get historical fiction or alternate historical fiction, which is considered part of science fiction.

There are so many subgenres to all this it isn’t funny. I’ve written enough for the moment.

I have a hard time with science fiction, I don’t really understand it. Some of the answers above helped though. So I guess as far as I can see, science fiction is like fantasy, only with ideas or concepts that have some kind of actual basis; and then it’s all blown out of proportion.
Fantasy on the other hand, just makes shit up.

The confusion for me is how both genres explain everything, or doesn’t. I think scifi has to try and explain things for it to be scifi, as it treats its elements as something very important to its premise, whereas fantasy is satisfied with saying that a wizard did it, and deals a lot more with drama.

True science fiction is based in actual theory; fantasy is pure, or mostly, implausible. The distinguishing factor is usually how much the author tries to explain regarding how everything works. In The Mote In God’s Eye Niven and Pournelle attempt to make a plausible story involving faster-than-light drive, and invented two devices to make this possible, the Alderson Drive and the Langston Field, however, except for those two devices, all else is legitimate scientific theory. Fantasy stories set their own rules to follow. JRR Tolkien created the best known fictional world with Middle Earth, devising intricate rules which it follows. Hell, he treated magic like a science, since it was a resource only for those disciplined to use it, and was limited by the world’s sources.

I have always used this as my rule of thumb. In Science Fiction, the stage on which the characters are set is explainable to them by the intervention of science and technology…regardless of how able they are to manipulate that world at the time the story takes place. In fantasy the stage on which the characters are set is explainable by the intervention of power possessing entities…your mother, the wizard, the gods, the planetary forces. Sometimes both exist in a single story. But that is rare.

In science fiction, the character will ask “how do they communicate without voice” and the answer will be something about the evolution of the species, latent telepathic genes.. and weak forces. In fantasy the answer will be that they are Enochian priests.