The essence of it appears to be,
Soft science fiction of either type is often more concerned with speculative societies and relationships between characters, rather than speculative science or engineering.
Soft-science fiction embraces the soft sciences (e.g., psychology, sociology, history)?
In my book, soft-science fiction is fantasy premised scientific-sounding conceits. Star Wars, for example, is what I call soft science fiction. Lightsabers and hyperdrives and S-foils are all about the pew-pew-pew! Hard-science fiction, on the other hand, is more real-world, limiting itself to what we are doing (but at a larger scale and/or in a different context of application), what we can do (in principle, but we have not gone there yet), what we will probably figure out (given some advances in technology), and finally what would require a bit of a miracle but which does not break known laws of physics off at the hinges.
I would say, for example, that
Gattaca is hard science fiction film. We can check the genomes of embyros for defects and we can select for the healthiest ones.
Gattaca just imagines this as a standard practice (a cultural arms race of health) which does a deep analysis, not just to avoid bad traits, but to select for the best traits. To me, this story considers the possible ramifications of existing science (IVF and genetic analysis).
Per the Wiki article, however, this would be soft-science.
My largest complaint with this view of "soft-science" is that literature has ALWAYS been concerned with the human condition.Literature has ALWAYS been concerned with describing human relationships and societies.
Under the Wiki definition most literature is soft-science fiction, as literature is just folk-psychology and folk-sociology applied to explaining "relationships" and "societies." Got a story that speculates about relationships in a society somewhat different that our own? Well, that's science-fiction! But, no. It really isn't.
Unless the movie explicitly purports to offer a fictional analysis of human relationships and society under the lens of Cognitive Dissonance Theory, or Need for Closure, or The Spiral of Silence, or Reversal Theory, etc., then the film is just doing what literature has ALWAYS done--offer a folk-psychological/folk-sociological explanation of motivation, attitude, values, blame, etc. (e.g., "He was jealous, so...") in a fictional setting. This is not science fiction! This is literature. LOL. And I can't think of any of the films, off the top of my head, that have titles announcing theories contained in an Intro-Psych textbook.
I suppose that there are some books that loosely tread on famous experiments that have captured the imagination (e.g., Milgram, Zimbardo), which have been loosely depicted one-trick ponies like
The Button. However, this would make our definition of soft-science fiction overly narrow. "Max Weber's
Bureaucracy coming to a theater near you!"