Easy peasy: IMAGINARY WORLDS

SUPERHEROES

Here is an interesting link to the various superpowers those heroes can be endowed with...
http://en.wikipedia.org/wiki/List_of_superhuman_features_and_abilities_in_fiction

FANTASY versus SCIENCE FICTION

Definition of the genres ( source : wikipedia) :

"Fantasy is a genre of fiction that commonly uses magic and other supernatural phenomena as a primary plot element, theme, or setting. Many works within the genre take place in imaginary worlds where magic and magical creatures are common. Fantasy is generally distinguished from the genres of science fiction and horror by the expectation that it steers clear of scientific and macabre themes, respectively, though there is a great deal of overlap between the three, all of which are subgenres of speculative fiction.
In popular culture, the fantasy genre is predominantly of the medievalist form, especially since the worldwide success of The Lord of the Rings and related books by J. R. R. Tolkien. In its broadest sense, however, fantasy comprises works by many writers, artists, filmmakers, and musicians, from ancient myths and legends to many recent works embraced by a wide audience today.
Fantasy is a vibrant area of academic study in a number of disciplines (English, cultural studies, comparative literature, history, medieval studies). Work in this area ranges widely, from the structuralist theory of Tzvetan Todorov, which emphasizes the fantastic as a liminal space, to work on the connections (political, historical, literary) between medievalism and popular culture."

"Science fiction is a genre of fiction dealing with imaginative content such as futuristic settings, futuristic science and technology, space travel, time travel, faster than light travel, parallel universes, and extraterrestrial life. It often explores the potential consequences of scientific and other innovations, and has been called a "literature of ideas".Authors commonly use science fiction as a framework to explore politics, identity, desire, morality, social structure, and other literary themes."