Tripple shielding is a "higher performance" method, or just aramidic/kevlar (fabric.) It's lighter, but less effective at stopping flats.
Double shielding is a fabric layer, with a dense rubber layer, it's heavier and probably has higher rolling resistance, but it's better for preventing flats.
Ultra shielding is a very thick layer of dense rubber, much like what the SMP has. A bit over kill, but the best way to avoid flats as tires go (I like tire liners a lot.)
http://www.vittoria.com/tech/puncture-cut-protection/
Vittoria Hypers are very similar to Marathon Supremes, but have a higher thread count.
Vittoria Randos are a less crazy version of Marathon Plus, somewhere between a HS368 and SMP, but are much more comfortable, and roll better than the HS368's in my experience. I'm guessing they're way more lively than SMP's, but I've not ridden those since they're so over priced.