[GeorgeMcFly]

I think its the way they are fished and what cycle of the insect life it represents. I believe the difference is that a soft hackle when swung in the current like a streamer represents a nymph coming to the surface to hatch or transform into the adult fly and a nymph when dead drifted is the beginning stage of a insects life when its underwater and hasn't came to the surface and hatched yet. its just crawling around at the bottom and gets swept away downstream. also a soft hackle can represent a spider or something thats fallen into the water if need be..