Re: Dubbing ?
Before there was the proliferation of synthetic dubbings that are now available, dry flies were primarily tied with the fur from animals such as Muskrat, Beaver, Otter or Mink, that contained natural oils which aided in keeping out the water & helped float them. The same furs could be used for nymphs as well, but plenty of weight had to be added to over come the tendency to float. Some materials also trap air better than others, so that helps with flotation too.
Rabbit, of course is an excellent dubbing for sinking flies, as it absorbs water readily, and there are other furs that do the same. When furs that did not float well were used to tie floating flies, they needed floatants added to the fly to aid in keeping them floating.
Basically, if you're selecting dubbings, or mixing your own, you'll want buoyant materials for floating flies & those that sink for sinking flies. There are now many blends that do both, and many colors.
As the others have said, texture is often a good indication of what a dubbing can be used for, but is not the only criteria nor does it guarantee the dubbing is suitable for a particular use.
If you're buying it, going with how it's labelled will usually result in the desired effect.
Remember, no one likes to be behind the big truck, but that's better than being under it!