Scene vs. Story

         What makes a short story a short story?
         I've seen a lot of questions about how the length makes a story short or not. To me, the the biggest issue is the story, not the length. So what is a story?
         Used in a wide manner, a story could be a quip you tell your neighbor about something that happened to you or someone you know. It could be a simple little explanation of how your tire fell off and someone stopped to help you who turned out to be a long lost cousin. Amusing, yes. A factual event, yes. It's a story in a way. But it's not, by definition, a short story. For that, you need growth.
         Characters make the story. After all, someone's tire falling off doesn't mean much to us if it's not someone we know or care about in some way. Yeah, it happens. And? The And? is what makes the story. The Who? makes the And? matter.
         That And? is the Growth factor. So something happened. Then what? Why does it matter? What did it change? If nothing changed, it doesn't tend to matter beyond being a possibly interesting quip to tell your neighbor. In all liklihood, he doesn't care that much, either, unless there's an And... involved, although he'll likely be friendly about it and act like it matters in order to be neighborly.
         Readers are harder to please than neighbors. They want a reason to spend time with your work, with your character, with your story. They want to know why it matters.

Scene: a little quip about something that happened
Story: an little quip about something that happened and what effect it had

For example:

         Andy looked at the log only a hop away. He could do it. He was physically able. It wasn't a long hop. His friends laughed at him for hesitating. He knew the only way to get them not to laugh was to take the leap, jump onto the log. And why not? He knew how to swim. The water was warm enough and the sun much warmer. He wouldn't drown or freeze. With a deep breath, he jumped. And he fell, hitting his arm on the log. But he managed to push the thing out of his way and swim back safely. Now he had to make up a story to tell his mom about how he got the bruise.

This is a scene. Something happened. Andy made himself jump although he was nervous. And? Is there any point to this event?

On the other hand:

         Andy stared at the log. It was the same size as the one his brother jumped on a hundred times to prove he could. The first 99 he sometimes fell off and sometimes stayed on. Jim's friends had laughed or cheered. Either way, he'd done it. He hadn't chickened out.
         That had been years ago. Jim no longer jumped. On anything. The hundredth time - or so it seemed to Andy - that he made the attempt, he fell off. Falling wasn't the problem. Hitting his head hard against the log was. Jim now counted on Andy: to push his wheelchair, to reach things for him, even to help Jim get dressed. Andy had never been a fearful child. He'd always followed his big brother in his adventures. Now, there was no more adventure. He didn't dare. What would happen to Jim if he wasn't there to care for him, if he hit his head, too, and couldn't jump, or walk, or dress himself?
         Of course they had their mom. But she was a girl and she worked hard already and Jim didn't want their mom to help him dress. How embarrassing would that be, Jim asked Andy. Those boys laughing at him for being scared didn't know. They didn't know how Jim got hurt. They'd moved to a new town. No one knew. Jim wouldn't say. Neither would Andy.
         "Come on, baby. Want your mommy to come hold your hand?"
         Andy cringed at the taunting. He couldn't go to seventh grade in a new school with boys who thought he was scared of jumping onto an old log in the pond. But he was. What would happen to Jim? To his mom who worked too hard and worried too much about Jim already?
         But how could he go to seventh grade being called a baby?
         He couldn't. He knew he couldn't.
         Jim had made it 99 times. Surely Andy could make it this once. He grabbed a deep breath. He focused on the log. The same size as Jim's log. He remembered the way Jim had jumped that way, running from farther away, jumping with his hands swirling over top his head. Showing off. Andy would do it different. Backing up, just far enough away to get a good leap to make it to the log, Andy let out the breath, took another, and sprinted, his hands to his sides, ready to cover his head. Heck, he could break an arm and still push the wheelchair if need be. He'd protect his head good.
         He felt his feet his the log, felt the log spin, felt his arms go up around his head and the log smacking the side of his arm. He went underwater, for only a second until the air pushed him back up. He reached out for the log and shoved it aside, his arm burning but still working fine. His legs still worked fine. He swam back to the shore. He heard the applause of the boys, mixed with some good-natured laughter that he fell in. But they all did, too. At least he tried. And he could still push the wheelchair.
         He'd make up a good story on the way home to tell his mom about the arm bruise. To Jim, he'd tell the truth. Jim would be proud of him for trying. Just the once.

This one is a story, a very short story. Why did it matter if he jumped? To start getting back to where he used to be before Jim's accident, before fear took over. Readers can see now that his life will be different than if he'd kept giving in to the fear. They can also see that some of that fear will turn into more caution than he used to have. Growth. Andy grew over the time span of the event.

Growth doesn't have to be in a character. Sometimes it's society. Sometimes it's the reader who grows as a result of the story (that's harder to accomplish). Something, though, must change, must make a difference. Always answer that And? in your story in order for it to be an actual Story. Otherwise, label it a scene, or vignette.