I grew up in the reading the literary science fiction of Asimov, Bradbury, Bova, Clarke, Dick, Ellison, Niven, Robinson, etc, and find those sort of stories to be very different than the way stories are told on Star Trek. I chose to call that former stuff "science fiction" and the latter "sci-fi". I love both things; one is not better than the other. However, both things are different. The latter having a "sciency or spacey" backdrop does not make it just like the former..
Although it may be worth noting that, even among the authors cited, there's a wide spectrum when it comes to their approaches to actual science and "realism." Bradbury and Dick and Ellison, for example, weren't remotely as concerned with getting the science right as, say, Asimov or Clarke or Niven. It says something about how big an umbrella "science fiction" is that we even try to lump Bradbury and Ellison in with the likes of Clarke or Niven. The former were basically fantasists who occasionally used sf imagery like spaceships and robots; the latter were more in the Campbellian tradition of hardish SF.
And, as for, "science fiction" vs "sci-fi" . .. well, yes, some old-school SF writers made a big deal out of that distinction back in the day, but I think that battle was lost decades ago. These days "sci-fi" is just a common and convenient nickname for SF and doesn't carry any of the connotations that people once ascribed to it.
At this point, it's like insisting that "Trekkers" are different than "Trekkies." It's a pedantic distinction that no longer matters to 99% of the world.
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