The title says it all. I know the difference between the extremes. But other than story length what is the difference?
My response would be that it's a different set of skills. In a nutshell, the short story requires one to be able to tell the full story in a very limited amount of space/time. The novel requires one to be able to sustain the storyline and reader's interest over a much longer time.
A short story is very short, so you have to get to the point and can't spend time developing chawracters, setting the scene and so on. A novel can be as long as you want it to, even spanning several books. It allows you to really take your time to develop the story to the fullest. For that reason a novel can in theory have dozens of characters, but a short story rarely have more than three or four. In a way you can think of a novel as the full story, but a short story is just a single scene.
Only difference is scope. On a scene by scene level, the depth and precision shouldn't be much different (if you're trying to write well). A lot of writers, often after seeing very bad examples of published, even successful works, think the difference between short stories and novels is a novel gives them time to dawdle. You know, the first chapter nothing at all happens except 'world building' and 'character building' and all sorts of things a writer justifies as acceptable because it's a novel. And sure, those things may be excused on occasion, but usually not by writers trying to break into the industry, and just because bad habits are excused in the work of established writers doesn't meant it's good writing technique. Saying a novel is a full story is equally misguided, in my opinion. Good writers learn the space needed to tell the story. Some stories can be told in a short space, some require more. It's not a matter of not being a full or real story, it's simply a matter of finding the space that works for the story you want to develop. A story about one character and the change that occurs based on a few key scenes is going to require different space than a story about 4 generations of 3 different families. One can often see stories that haven't found the proper space and are either compressed into a form too short or extended out into a form that's too long. Ever read a novel that seems to go on and on, saying the same thing about the character, 'building' the same setting and world over and over, scene after scene effectively showing us the same thing? Or a short story that reads like the summary of a longer work? This is all bad, obviously. And the difference has little to do with how a story is written on the nuts and bolts, sentence level, if you're doing it right. A good short story and a good novel will both be doing the same things from a technique perspective, a novel will just be doing it for longer, to accommodate a story with a broader scope that requires more space. It's a mistake as a writer to think you can take it easy or add in expository writing just because it's a novel and will be excused. The story should dictate the space it requires to be told fully and completely, not the other way around.
^This. A short story is a very economical form. Generally, everything that happens in it should advance the story directly. You don't have the luxury of straying like you might have in a novel where you can spend time on backstory, side plots, characterization that's not directly forwarding the plot, etc.
It's either a novella or a novellete. The terms are rarely used, but it's how the book agency categorize it by it's word count.