Drop't in to See the Widow,
John G. Brown ( 1831-1853)
oil on canvas.
Someone, somewhere, (my usual source) commented recently that this electronic generation - partly because of time constraints and the ADD syndrome induced thereby - are particularly open to lunch-hour reads, and writers should not get their Shorts in a knot. Source suggested that anthologies and short stories and novellas would grow in popularity because they satisfy a quick 'n dirty need.
About the same time I came across a publishing term, unfamiliar to me: Chapter Books. Seems children's Chapter Books, designed for the transitional reader, contain about the same word count as a chapter in an adult novel or the average short story.
Some people offer chapters of novels on their sites in serial style.
Some writers create addenda-type/backstory/prequil short stories which expand characters, themes and incidents from their published novels. Some writers' short stories become chapters in a later novels.
So, though the question may be based merely on semantics and thus on a distinction without a difference - like turning one's undersilkies inside out - I wonder if we might see another form emerge in publishing.
One shorter than a novella, self-contained and episodic around a central cast of characters - like a mini-series.
A formal, adult "chapter book."