The M-DISC, on the other hand, has "actual pits are burned into the recording medium by a laser." M-DISCS are still readable by all DVD drives.
As you can tell from the picture above (via Register), M-DISCS have the same base but are less susceptible to corruption thanks to an "inorganic and synthetic material" data layer.
M-READY drives also engrave the pits in the surface of the disc, for a rock-like surface.
Furthermore, the discs will have somewhere in the 25-50GB range for capacity, well above standard DVDs. The company has partnered with LG, who will release a Super-Multi Drive that can read/write M-DISCS, Blu-ray and DVD. No word on price, yet.
You can read more the technical aspects of the disc here: Accelerated Life Cycle Comparison of Millenniata Archival DVD