Wooly Bugger vs Wooly Worm
What's the difference? The book I'm using, The Art of Fly Tying has the Bugger with a Marabou tail and the Worm with hackle. I cheated and substituted some Krystal Flash (I think that's what it is) for the hackle.
Is there a standard understood difference? I had used the terms interchangeably before this and tied whatever tail seemed handy at the time. Now I'm wondering. How many woolies are there?