There are two basic types of protection against punctures. One is to have a thin, flexible but hard to cut fabric-based layer (Kevlar/Aramid, Vectran, etc.) that basically "catches" objects as they come through the tread. The other is to have a thick, hard layer of solid material embedded in the tire that attempts to block punctures. The fabric approach is very good against relatively large objects like chunks of glass, but it fails against things with a very fine point like the wire you mentioned. The solid material approach is more consistent but it's heavier and doesn't roll as well.

The Durano Plus and the Marathon Plus both use the solid material approach, but the layer of material is significantly thicker in the Marathon Plus. This will make it much more puncture resistant, but at the cost of extra weight and rolling resistance.