Neverbend,
The details you are asking about are much better illustrated with examples than words. It reminds me of the pipemakers forum when a new carver posts photos of his first attempt alongside pictures of the pipe he tried to copy. There's really nothing you can say other than, "They aren't the same. Keep looking until you spot the differences."
The easiest and best way for someone who is interested in such differences to see them is to have two pipes literally in hand, and compare them side by side. Then, when you're finished and think you've spotted them all, hand the same two pipes to someone like Adam Davidson who will show you what you missed.
Me writing about such stuff would branch endlessly, Mandelbrot Set-style, as questions and answers layered upon themselves. It would be like trying to write an interactive book.
As cool as something like that could potentially be, I honestly haven't the time.
Maybe you could start a new thread that showed full, close-up photo sets of two pipes, one of them factory Britwood and the other a prime Danish or American specimen of the same shape, and open the floor to comments about the differences that can be seen. Such a thread would also be more informative and entertaining than me writing pages of attempted description.