These two genres are considered largely similarly, despite vast differences between them. They’re both kept in the same section of book stores, they’re both definitely ‘nerd’ books, and they’ve both been a part of the explosion of recent sci-fi/fantasy movies, between LotR/Harry Potter, superhero movies, or Star Trek.
They have one thing in common, that distinguishes them from typical literature; whereas fiction describes events that occur in a world that is largely our own, these genres tend to describe events in a world that is significantly different from our own. That is, science-fiction and fantasy are both speculative fiction: they answer questions of the form “what if…?” This is why we consider novels like Brave New World, 1984, and Harrison Bergeron to be science-fiction of a sort (they are typically referred to as ‘speculative fiction’). But from there, they diverge wildly. To sum it up, with a quote from Miriam Allen de Ford: Science fiction deals with improbable possibilities, fantasy with plausible impossibilities.
Mythology vs Prediction
Ultimately, what the distinction comes down to is simple: fantasy is an extension of the religious/mythological storytelling that was common in many traditions, including the Judeo-Christian and Hellenic traditions. As such, fantasy carries with it the tropes of mythology. Science-fiction, on the other hand, could be seen as having been birthed (with a few exceptions) in the Enlightenment. During the Enlightenment and the subsequent Industrial Revolution, the world changed HUGELY, and science-fiction was born of people saying ‘and what happens if it keeps changing?’
Essentially, fantasy is envisioning the world as we might want it to be or have been, while science-fiction is trying to predict how the world might be. That is, fantasy is an inherently nostalgic genre, while science-fiction is an inherently transformative and visionary one. Do not mistake this to indicate any sort of tone towards either genre. As a liberal atheist, I find the science fiction viewpoint more compelling, and yet I find myself personally more interested in fantasy (and mythology, for that matter).
Transferability of Power
Another common distinction is in the manner of power in the universes. Power, in fantasy, inheres in things. This is represented in two ways. First, fantasy tends to be ABOUT individuals, and about how they are in some way uniquely suited to their task. Even Frodo, one of the most powerless characters in fantasy, is described in this manner often, as many characters marvel at the mental fortitude and willpower of hobbits; their ability to endure. Fantasy is filled with tropes of power that inheres in a person:
- Only The True King of Albion (King Arthur) can pull forth Excalibur from the stone.
- Gandalf didn’t LEARN magic, it’s just an inherent quality he possess as a being from another plane.
- Harry Potter is ‘The Boy Who Lived’; nobody else could ever kill Voldemort.
The second way in which this is represented can be summed up by the following claim: things take on the nature of their owners/origin.
- Only Sauron can use the One Ring; anybody else will be corrupted by it.
- The Dark Side inherently corrupts, you cannot simply use it as a tool.
This differs highly from Science-Fiction, where power is ubiquitous: anybody can use a laser or a spaceship or time travel or whatnot. They may not use it well, but nothing prevents them from using it. If a Star Trek mechanic made a new laser, and it fell into the hands of the Klingons, they could use it just fine.
We even can see this in the idea of ‘destiny’, a common theme in fantasy which rarely crosses over to science-fiction. Destiny is the ultimate way of power inhering in a person; they are the person who will save the world by virtue of being them. Nobody else could do what they could do, simply by being somebody else.
Finally, fantasy is filled with ‘mystic guides’. These mystic guides exist solely to guide the protagonist on his quest, but they could never do what he does. Why can Merlin not be king of Albion? Why can Obi-Wan not fight Darth Vader? Surely they are stronger than some boy they must train up? But the tropes of fantasy mandate that it is not just about power, but about being the right person.
This very much mirrors our nostalgic view from above. If you look longingly to the past, you might see things like monarchy and divine mandate in a positive light. While few people would actually admit to that on account of cultural values, it does seem to fuel this nostalgic desire. Why does Aeneas found Rome? Because it is his destiny. Why does Troy fall? Because the gods willed it. Why will the apocalypse come? Because God has mandated it.
Simplicity vs Complexity
Another way in which fantasy typically differs from science-fiction is in regards to how it sees complexity. Fantasy tends to have clear-cut good and evil, where science-fiction doesn’t necessarily. Star Trek is all about not interfering, and I, Robot features a bunch of short stories that leave you questioning your ethical views. This is especially true in speculative fiction like 1984 or Brave New World. On the other hand, from the moment you meet Sauron or Darth Vader, you know he’s ‘the bad guy’, no questions asked. This isn’t to say that there isn’t grey area of morality in fantasy
As far as the unknown goes, science-fiction seeks to understand the unknown, and reduce its domain. Fantasy, on the other hand, lifts up the unknown and idolizes it.
Setting vs Tropes
It’s at this point that I must make a divergence. You see, I keep giving examples of fantasy that include references to Star Wars. This is because it’s very important to distinguish the trappings the world is dressed in (the setting) from the tropes in the book (the genre). For example, if Lord of the Rings took place in space, with space wizards and space orcs and space hobbits who just wanted to go back to Earth, it would still be fantasy. The ring would still need to be corrupting, it would still be important that Sauron and Gandalf and all of the otherworldly beings were otherworldly. You cannot have LotR without the ring corrupting, or without Gandalf and Sauron’s powers being largely inexplicable, or you entirely change the tone of the book. And it is with this terminology in mind that I posit that Star Wars is a fantasy movie that happens to be wearing a sci-fi setting. You might confuse it for science-fiction; after all, it takes place in space, and there are lasers and spaceships. But the movies aren’t about those things. They are about lightsabers used by a select few. They are about the Force, which bears the power of its user, and is not just a tool, but a lifestyle. Star Wars is about a strong good and evil distinction. It has a clear villain and a metaphysical guide (Obi-Wan) and an idea of destiny.
People only involved with sci-fi/fantasy at a surface level (blockbuster movies), might see the setting as the important distinction. In this case, their definition of sci-fi is something like: X is sci-fi if it has sci-fi tropes OR a sci-fi setting (actually, some people may even go so far as to say: X is sci-fi if it has a sci-fi setting). This is part of why my definitions may seem counter to common terminology. I respect this distinction, I suppose, but I don’t think it’s an important one; a bear wearing a suit is still a bear.
Obviously, these all fall along a spectrum, and you are going to have grey areas, so keep that in mind.
TL;DR Science-Fiction is about revolutionization, fantasy is about nostalgia, Star Wars is just a fantasy novel about paladins that happens to take place in space.