DLC is a complicated class of materials, generally composed of amorphous carbon (no long-range order - kind of like glass) with the same kind of interatomic bonds you see in diamond (sp3 bonds). It's often applied by sputtering or ion beam deposition.
Diamond is sp3-bonded carbon with long-range crystalline order. It's most often made by chemical vapor deposition, which is slow and expensive compared to DLC deposition methods.
The DLC coating described in the article won't do much to reduce glass breakage. But it will greatly increase scratch resistance because it's nearly as hard as diamond.
Diamond doesn't melt unless you're heating it while it's also under enormous pressure to keep it from turning to graphite. It does ablate, or vaporize when hit with laser pulses. This is used to remove small graphite inclusions in diamond.