The shorter ones are a little taller than the longer ones and they weigh about half as much. Because they are taller they can have a similar effect concerning "catching the wind" and steering the arrow that the heavier long vanes have. Feathers ( I have not used them yet but am getting some tomorrow) are long and present a larger surface to "catch the wind" and steer the arrow but are light so you kind of get the best of bothe worlds. But then, in inclement weather, feathers (from what I am learning) can get wet and misshapen.

The type of vane or feather you use is determined by what you need to accomplish with your arrow. I am using blazers on my present arrow because 4" vanes would make the spine to stiff (extra weight to the rear of the arrow). If my arrow had a weaker spine and I needed to make it stiffer then I would use the heavier, longer vanes. I choose my fletching based on the arrow and how I am building it, not on how it will look when finished.