There are many different aspects to consider when writing a short story, and a novel. They are two completely different genres which require their own unique style in story telling. Personally, I think of short stories as exercises which one can do in order to get in that culture of finishing a piece, whether its 1K words, or 10K words or even a 100K one.
One of the main challenges when writing a novel is to actually flush it out in a way that is still engaging. Any sentence you write should build up for something larger or give hints towards something that needs explaining; you simply cannot get away with writing fillers in a novel (stuff completely irreverent to the story just for the sake of increasing the word count).
In short stories, you can actually get away with a lot of things, for example you can skip an entire battle or a change in sequence… moving forward with the story in just around 500 words (something that cannot be forgiven in a novel). Some might argue that this does not reflect good practices, to which I say, who the hell sets the rules for writers? We ourselves do.
Think of it like this: in a short story, you can sum up a huge event with its outcome and just proceed to the aftermath. In a novel, you have to explicitly describe everything that happened, no excuses!
Writing short stories is always fun, as you essentially get the culture of actually finishing a project, and that momentum is what gets you going when you’re writing a novel. You will never improve if you keep writing in your comfort zone… you have to extend it and explore different genres in order to increase your vocabulary.
Until next time,