I think a major defining feature of science fiction is the necessity to describe the setting. Maybe hard science fiction would not need as much exposition, but a good sci fi novel will spend some words involving the reader into the setting. I guess this will overlap quite a bit with fantasy, but the exposition should clarify the rules of the universe such that the reader can understand the general interactions between characters and settings. Some "sci fi" just makes a weird or disjointed setting and passes it off as radical or revolutionary, without ever giving the reader a chance to get grounded.
I think a major defining feature of science fiction is the necessity to describe the setting. Maybe hard science fiction would not need as much exposition, but a good sci fi novel will spend some words involving the reader into the setting. I guess this will overlap quite a bit with fantasy, but the exposition should clarify the rules of the universe such that the reader can understand the general interactions between characters and settings.
Some "sci fi" just makes a weird or disjointed setting and passes it off as radical or revolutionary, without ever giving the reader a chance to get grounded.