[chongli]

It's basically fantasy except the magic is, to varying degrees, rooted in real science and physics.

That's a superficial view of both Sci-Fi and Fantasy. Sure, there's a lot of schlock out there which essentially functions as this sort of meaningless escapism for the reader. But proper Sci-Fi and Fantasy is philosophical in a way that makes them radically different, if not diametrically opposed.

Fantasy stories typically depict a society in decay, with evil ascendant, and characters who yearn to return to a time of past innocence. It's ultimately backward looking and conservative. When it functions as social commentary, it's a critique of the alienation and impersonality of modernity.

Science Fiction is forward-looking. It asks "what if" questions about the limitations of our modern society by inviting us to view a society that has been freed from those limitations. It challenges our ideas about human nature. It's ultimately progressive, even when it depicts dystopian governments.