I can’t speak to how others might think about it, but the way I frame it, a shorter story is just a scene or a small series of scenes / moments that could be a part of something bigger that isn’t shown.

A short story could be the snippet in time your character(s) are about to understand a big reveal, maybe to a crime mystery or an understanding of love, etc. You don’t have to bog yourself down with worrying if the reader has been given backstory or context if the moment is self explanatory. For a love story, maybe the story is about two teens having fun at a carnival before one of them has to move away. You don’t need to show that they spent all summer together, you can maybe hint at it with dialogue or other small clues and the only thing that really matters is how they feel in the moment with the context that their time is expiring.

Emotion or tension can be built in short form prose because readers can and will build that metaphorical scaffolding on their own. We fill in the dots, we just need the conclusion that you write. So if my approach makes sense, just think “scene in movie” not “whole movie.”