I did some extensive reasearch, here is what I have found. Helical and spiral wound wires are the same thing, different manufacturers use different names. The big difference is how the conductor is built, such as how close the windings are and how much ferrite the wire has for added noise suppression. The looser the windings and less ferrite the noisier the wires are ( also cheaper to build ). The cross section of the conductor (wire) matters more than how low the resistance is. Low resistance is good, but too low and not enough noise supression. I had a set of Taylor 10 mm wires, after they failed I cut them apart and found a wimpy little wire inside, loose wound on a thin core, and didn't see any ferrite ( black coating on conductor). A stainless steel conductor is also better than copper because it is much stronger. I guess some use copper because it is cheaper. It seems the overall size of the wire doesn't tell you what is inside. I got alot of info from Aurora
www.auroraelectronics.com, they have tech articles and actual cutaway pictures of their wire, ( not a diagram that gives no real reference to size ). The website is not totally complete or that flashy, but I would rather get a good product than alot of hype! I have come across more and more people using them and no complaints. I have put up a few postings about these already because I really believe in them. Worth a look, then make your own choice.