How is science fiction different from fantasy?

In my opinion Science fiction explores what is possible (even if it’s improbable), while fantasy explores the impossible. For according to LeGuin (2005b) Credibility is what keeps the readers attached and absorbed in any fictional work. This means that their might be a chance that fiction has the ability to happen in reality while fantasy is built from the mind or the imaginations of a person.

 Science fiction is really sociological studies of the future, things that the writer believes are going to happen by putting two and two together . . . Science fiction is a logical or mathematical projection of the future. Science fiction is sometimes based on true events and settings, science fiction works usually sets on what's on ahead of us or sets in the distance future. Rarely this sort of storyline catches the interest of the readers to continue on reading and finding on what happens next.  

While science fiction draws on and extrapolates from what we know about reality and science, fantasy invents what does not (and likely could not) exist in our reality for example according to Attebery (1980) claims that fantasy is any narrative which includes as a significant part of its make-up violation of what the author clearly believes to be natural law. There are various ways a story can proclaim its fantastic nature. He relates fantasy with some other stories written by other authors including: Tolkien The Lord of the Rings, Lewis’ Narnia and Perelandra books, The Wind in the Willows, the Alice books, The Princess and the Goblin and all of George MacDonald other magical stories. These are all similar fantasy stories where impossible beings came to life such as goblins, mermaids and supernatural creatures that goes beyond our imaginations. Fantasy is a tool for the writers to either sell their books to earn more benefits and under any circumstances make us believe that this could possible come true. This is similar to a child's imagination. 

References:

LeGuin, U. K. (2005b). Plausibility Revisited. Retrieved from http://www.ursulakleguin.com/PlausibilityRevisited.html

 

Attebery, B. (1980). The fantasy tradition in American literature: From Irving to Le Guin. Bloomington: Indiana University Press.