Scriptmag.com recently featured an interview with Diane O'Bannon, widow of Dan O'Bannon who co-wrote "Alien" and "Total Recall", and Matt Lohr, who completed a book Dan started (he wrote about 75% of before he died). It's called "Dan O'Bannon's Guide to Screenplay Structure" and it's published by Michael Weise Productions. One point they discussed is what constitutes a story:
DIANE: The thing that’s surprising is people often don’t get what a story is. How about Prometheus? Prometheus is a fabulous film, it’s visually stunning, but it’s not a story. It wanders. At no point do you feel like you know who to watch next. Ridley Scott is a fantastic filmmaker, but he didn’t think it was important not to frustrate and anger a lot of viewers. Or he didn’t notice that he didn’t have a story that went from A to B, that brought you up, that brought you down, and completed itself.
MATT: A string of incidents is not a story, even if they involve the same characters. Prometheus is a string of incidents.
What's the difference? Largely it's cause and effect.
Each major incident in a story has an effect on the characters, although it may not be immediate. In fact, often it's more interesting if it's not immediate because it allows us to speculate what the consequence will be.
If you provide a mixture of what we expect and what we don't, you create a satisfying experience.
We also expect stories to have a beginning, middle and end. That's not to say an ending can't leave room for interpretation, but it shouldn't feel like you just decided to stop writing.
(You can get lots of tips about creating characters and powerful stories, in my book "Your Writing Coach," published by Nicholas Brealey and available from Amazon.com or your other favorite book seller.)