What are the differences between Columbus Tubings? I'm just wondering why there are seven kinds of tube sets by Columbus (or Reynolds). There's XCr, Spirit, Life, Zona, Max, SL, and Cromor. I recently had a frame made using the Cromor tubeset; mainly because it was the cheapest set they have. Now I'm wondering what really is the difference between the other sets and why they cost more.

I read the product catalogue, it's mostly about the material used and mechanical characteristics, which I'm not really familiar with. Could someone explain the differences, as well as pros and cons, in layman's terms?
The Bicycle Info Project has a nice page at http://www.equusbicycle.com/bike/columbus/columbuschart.htm that describes the different Columbus tubesets in layman terms.  The following is a sampling of what is on the site.  The information gets even more specific relating characteristics to particular tubes (e.g. top tube, seat tube, chainstays, etc..)