[Nonfractal]

Apart from the obvious can someone explain the difference between plain copper braids and the tinned copper variety please? Is one better than the other for different types of tracks?

Brian, 
Tinned braids are constructed from strands that are coated in a metal similar to that used for soldering, prior to the braiding process. 
One better than the other? 
I have not found one  to work better than the other on steel rail tracks. 
I'm sure others will have opinions. 
Alan