Sci-Fi: sub genres

What are the codes and conventions of the Science Fiction genre?

A Science Fiction film is set in the future, either on earth or space. Sci-Fi includes futuristic technologies to explore social, political, and philosophical issues. The stories that are told in the Science Fiction genre are often in a world that is very different from the real world. In sci-fi, a hero would be found on a quest with either an arrogant or self-doubting personality. The hero though is never alone his/her journey with a sidekick/mentor being in place to help and the death of the sidekick/mentor creates a resolve for the hero to save the world in the final act. Now without evil, there would be no need for any saving of the world so the hero often needs to fight an Alien or non-human threat with the villain being stubborn and arrogant. The villain has soldiers or cronies that do the dirty work of him/her which the protagonist deals with leading up to the closing act.      

(The script Lab, Wikipedia & slide Player) 

What are the different sub-genres of science fiction?

Apocalyptic Film: An apocalyptic film is about an impending disaster. The Apocalyptic event in the film is usually an alien invasion, nuclear war, pandemic, or a natural disaster. Technology plays a large role in these films and often serves as a source of conflict. While many films that have the apocalypse as its theme often center around the disaster, some can also focus on the world after the apocalyptic event.

Dystopian Film: Dystopian film is a sub-genre of Science-Fiction film that shows the ruined state of the world. These films take place in the future in a world that is infested with violence, oppression, and disease. A Dystopian film often has the same themes and characteristics of a post-apocalyptic film. The common themes that are in Dystopian films include dehumanization, the repression, and uniformity at the cost of human rights. The blade Runner films are a good example of Dystopian film.