Every mode of story-telling -- movie, novel, comic book, role-playing game -- differs in what it can tell, and how it can tell it. Learning how to do one may habituate you to useful skills, and to positively counterproductive practices, for another.
One I have seen recommended for writing is playing role-playing games, and so I will talk of some of the counterproductive practices. These will apply particularly to the Dungeon Masters who run sandbox worlds, where the characters wander as they please, but there's difference inherent in the genre.
This starts with the players sitting down to make their characters. The game will have three, four -- eight -- characters, all of whom deserve focus. And they are the focus. Beside them are the NPCs, who may drive plot as the villains and have lives outside the PCs' attention, if only so they can, as wandering monsters, make the PCs stop lollygagging, but they do not get the focus in the same way. An NPC stealing a scene makes PCs unhappy.
A novel rarely manages to pull of the trick of having more than one main character. Even having more than one major character can be a real trick.
But around that one character extends a sliding range of characters from his best friends and worst enemies, out to the people who are effectively wallpaper, there to lend credence to the existence of the world. With all of these characters orchestrated to support his story, as foils, mentors, plot devices, and many more purposes.
It is wisest, generally, to start with the main character -- or at least one character -- and introduce even the most major characters one by one about him. Give each character a chance to show his stuff in isolation. (And since the reader does not know who is important, those characters introduced with extra flair are a hint. The royal court dazzles the heroine? Let the plot-significant prince arrive late to dinner, so she has a reason to pick the arrival out of the glitter.)
But however they are introduced, all of these characters, including the main one, can rise and sink in importance. A character can flare up to steal a scene and never appear again, and major characters can leave the story entirely. For that matter, the main character can leave the story entirely. It's a hard trick to pull off even in the first chapter, and gets harder the longer the story goes on, but it has been done with artistic success. No character is necessarily required.
It is not a matter of the wizard's dying at the goblins' hands only for the party to discover that the goblins held another wizard prisoner. Two, three, four wizards may be added to the group at need, only for the first -- or one of the new ones -- or all of them -- to leave at need.
Plot need, of course. On the other hand, you have justify it. Story characters need motives. Backgrounds. Purposes. Players identify with characters and do not require the DM to make them sympathize with the PCs, no matter how flimsy they are. Novelists have to work up the characterization to make the reader care, to admire the admirable ones, to hope for the character arc of a flawed one, to hate the odious ones.
Thus they need sufficient backstories for their story and a motive to act as they do -- if the world is in danger is sufficient motive for them, why is it not for every other character they meet? -- and a reason to associate with such other characters as they do.
Such associations can be loose, of course. There is no defined central group, all associated with each other, unless such a group serves the story, and they need to work together plausibly. A master wizard knows a locksmith who, of course, knows a few ways to pick locks, and a couple of guards on the royal castle because they generally assigned to escort him to royal audiences, and a priestess at the temple of the god of magic. The guards know each other, but all the rest do not necessarily know so much as of each other's existence
Even if they spend the story traveling, which strongly differentiates between the traveling group and the minor characters they meet, perhaps the guard on a caravan knows a wizard who consulted him for whether this was a good caravan to join, a merchant driving his wagon, and a boy who works for caravan master without any of them knowing each other.
At that, perhaps the wizard leaves at the next city and the story follows her as well as the main character. Splitting the party is, or at least can be, a positive advantage in a novel. It allows the development of other characters, encourages subplots, and gives rise to dramatic irony. No player appreciates the dramatic irony of other players' knowing something important to his character while he remains in ignorance, but it's a great charm in fiction.
And all this is, of course, just brushing on the topic. Anyone who both writes and runs games will find many more contrasts.
My weakness as a DM has always been that I am too much of a storyteller. I find it hard to adapt to the players’ unanticipated choices and actions that divert them from what figured was the plot.