Did you know there are about 45 sub-genres of science fiction?
I looked them up. Some I had never even heard of! Do you know any of them? Examples: Afrofuturism. Alien Invasion. Anthropological science fiction. Black science fiction. Biopunk. Comic science fiction. Cyberpunk. Deco punk. Diesel punk.
Not so much Genres as Themes. Standard settings for the given story, This tell the reader a lot about the background, and without it backgrounds become very difficult to fill in, presicely because Science fiction is usually about science that does not exist in current reality. How would you explain the impact of automobile to someone who only knew Horsedrawn transport? How would you explain the need for "the New Jersey Turnpike" and for multi-storey parking garages to that reader ?
@Jakob & Shar to the Rona, HarLon Ellison is listed as an American writer of short stories, novels, essays, and television and film scripts. His principal genre is "speculative fiction". This is also on my list of genres. He also writes fantasy, mystery, horror, and film and television criticism.
I will post the definitions of the two genres you mentioned, Shar.