When we see the bullet proof vests on foreign correspondents, they are basically kevlar with ceramic trauma plate inserts roughly from 5" x 8" and 1/4" thick for concealed vests, to 10" x 12" plates up to 1/2" thick for tactical vests. They work in combination with the aramid fabrics: high ballistic protection from the plates, dispersal of blunt trauma from the fabrics.
Boron Carbide: B12C3 for those who understand such things is exceptionally hard because the molecules form a network plane. Not a new technology, it was first synthesised in 1899. The discs in the Dragon Skin are silicon carbide (SiC) or carborundum, used since 1893 as an abrasive. thank you wikipedia. Both these materials have a zillion other uses: something about how their molecules arrange themselves in dense interconnected plates makes them exceptionally inert, resistant, hard and defensive.
The small overlapping plates of the Dragon Skin allows more motion and is designed, evidently, to absorb multiple hits, which is a sobering thought. All of these are meant to protect vital organs, not to render someone entirely bullet proof. I expect that development in ballistic technology forces the development of anti-ballistic systems. There is, for example, something called a full metal jacket bullet which is a soft lead core fully jacketed in hard metal which allows higher velocities as the hard jacket slides more easily down the bore. Do I want to know this? I suppose so, I thought the movie Full Metal Jacket was actually about some kind of armoured jacket for soldiers. The point of a full metal jacket bullet is that they can be used indiscriminately against both soft and hard targets. I think I'll leave this topic now.
There was a scandal in 2007-8 where the US government did not equip its soldiers in Afghanistan with $5000 Dragon Skin armour, choosing cheaper armour from companies with government contracts. Some things never change.