The constant comparison between PHM and Iron Lung makes a great case study in genre techniques. How a difference in genre shapes two trajectories which start off with a similar initial premise. (Stars dying, guy forced to be in thing meant to find solution, someone having to take him there, alien encounter, etc etc.)
So you can have a story idea or premise but the genre you pick for it matters because it will affect the overall outcome of the structure, plot, character arcs, and so on.
Genre is sorta like the dyed water to a rose seed of an idea, you can have the same seed come out with different vibes based on the dye you pick. (Granted the admittedly faulty analogy implies the changes are merely cosmetic, but you get the sort of idea)
I guess a better analogy would be like what you feed Eevee in Pokémon when you want to evolve it. You get wildly different outcomes with similar backbones when you pry inside.