February 14, 2020:
In his 2016 textbook Brevity, David Galef defines "vignette" this way: "an illustrative scene, a literary sketch". He says, it "isn't a proper story with a beginning, middle, and end." Yet, the two examples he cites, Collette's "The Other Wife" and Isaac Babel's "An Incident on the Nevsky Prospekt", do not exemplify this definition. They do something else entirely. They're simply short examples of "story", exemplifying the same definition of "story" you were taught in grammar school: a narrative with a beginning, middle, and end, where events occur, which in some way change the protagonist, who undergoes "character development".
Collette's story begins with a married couple entering a restaurant, where the husband spots his ex-wife. It consists mostly of its middle section, in which the couple discuss the husband's ex and the failure of that relationship, while the wife becomes more meditative. It ends with the wife seeing her husband differently, thus questioning the viability of their union. Beginning, middle, character development, end. It's a perfectly ordinary "story". There's nothing special about it because of its word count.
This demonstrates, I think, the power over us of the things we've always been told, irrespective of our attempts to free ourselves. Galef thinks he's demonstrating something which he in fact is not. This isn't merely the unconscious hold of the dominant ideology, although I think it's likely there's that too. I suspect part of the difficulty we have in escaping the grammar school definition of "story" is that as a definition it lacks something it specifically requires if it's to be usefully delineated. Beginning, middle, development, end: these things take place in a line. A sequence constrained by the arrow of time: the events unfold in a single dimension in a single direction, where their causality is deterministic, and they lead, if the story is expertly written, to a conclusion which is already present in its beginning.
Every "story" is a romance of Time's Arrow, an epic of the Second Law of Thermodynamics. A character "develops" because it exists in time and because time moves in just one direction. Every "story" is by definition a line: a one-dimensional entity. This is as true of Collette's "The Other Wife" as of War and Peace. This is why they're both "stories", and why neither is a vignette.
You'd think we'd all be trying to get away from this. Twentieth Century science was all about nondeterminism: logics of complexity, of probability, of new causalities. Literary forms have tended to follow science for at least the last couple of centuries: Modernism followed Relativity, Postmodernism followed Quantum Mechanics. Why aren't there new literary forms which follow the last century's fascinating breakthrough logics of indeterminacy and probability?
Part of the answer, I think, is that we've been constrained by the forms of distribution our works were forced to conform to. If your work is distributed in print, the binding forces consumers to experience it in a linear way, regardless of what your authorial intentions might be. Well — that's not literally true of course. The codex is a random-access medium, you can read it randomly or backward if you choose to. My mother always read the final chapter of mystery novels first. For her, the art of it was how the author got you there when you traversed it "properly" from beginning to end. That is, she read specifically to enjoy the author's technical expertise in manipulating the logic of deterministic causality and the arrow of time to begin somewhere specific and end somewhere necessary while twisting the "plot" around for fun and diversion.
Whole genre exist to exploit these constraints. Detective fiction, obviously. Picaresque: Tom Jones is always going to London, will always meet Mrs. Waters at the same inn in the same way at the same moment no matter how many times you read the thing. That's the art of it, and, interestingly, it's an art which is forced by the medium of distribution. The novel, like the "story", is by necessity a one-dimensional form. Skilled authors have been wonderfully inventive in developing techniques which exploit that one-dimensionality in entertaining ways.
More than merely entertaining. That there have been attempts to escape linearity within a linear medium is at once both heroic and a little ironic. There's been great art: Citizen Cane is nonlinear, as is much literary Postmodernism. The irony is that while the narrated events are narrated in non-chronological order, the experience of reader/viewers is nevertheless the same with each re-engagement. They encounter the same events in the same order each time through the work. And, they all do. Every reader/viewer experiences those exact events in the same order every time. Citizen Cane is in fact not nonlinear at all. It's non-chronological, but it's totally linear. It can't not be! It's a film. This is how the medium of distribution constrains and to at least some degree comes to define the work.
Digital media make it possible to add dimensions. In a virtual world such as TriadCity, I may walk my character along the same route a thousand times without ever repeating the identical experience. I might interact with non-player characters which weren't there previously; or chat with human players I've not met before; or the route itself may have evolved, for example by changing from day to dusk to night to dawn. Because TriadCity imposes subjectivity on participants, you and I may walk our characters together along the same route yet experience it subtly or profoundly differently. Digital media thus introduce new forms of narrative causality which are now probabilistic rather than deterministic. As a TriadCity author I can write a fork in the road, with a sign pointing east reading "Really cool stuff this way! -->" and another pointing west reading "<-- Nothing too much to do over here.". Yet we can be certain that some percentage of participants — most of them, in my experience — will make a point of taking the western fork just to learn what's there. Granted that behavior, world authors may want to locate the really interesting content in that direction, where now participants have a classically Modernist unreliable narrator to parse and outguess. In TriadCity, participants can experience four dimensions: east/west, north/south, up/down, and change. Fiction writers have only comparatively recently had canvases available which provide this level of potential experiential richness — and are still learning what to do with them.
Perhaps perversely, vignettes are a form which have the potential to rebel against the one-dimensionality of "stories". Perversely, because a vignette has no dimensions at all. It's a point, not a line. A snapshot, not a film. Like lyric poems, vignettes can escape time's arrow by preventing time from existing at all, or constraining it to the most minimal boundaries which disallow "character development" in any meaningful sense.
This is why literature teachers and workshop leaders instructing contemporary authors to "write digital stories" are reactionary. They're like early film producers who believed movies should be single-camera documentaries of stage plays, performed live, without edits. That is, simply a new medium of distribution of an existing form, rather than a new form with vastly expanded capabilities.
And it's why David Galef's account of the two stories he references is garbled. Brevity — word count — is not the determinant. It's the medium of distribution that decides.