Science fiction is a genre that uses speculative, fictional science-based depictions of phenomena that are not fully understood and accepted by mainstream. Themes can include futuristic elements such as spacecraft, alien worlds, time travel, robots, cyborgs, parallel realities or other imaginations of ideas and technologies that we haven’t seen yet, but still fit within our understanding of the universe. Fantasy on the other hand is more concerned with magic, myth, vampires, werewolves, creatures and may lack any proof of reality.
Erotic stories plots can also take place in alternate universes or undiscovered dimensions of the planet. The setting can be from a medieval tone with characters that many readers would deem as strange.