GideonTech has posted a comparison between HD DVD vs. Blu-ray. Here's an excerpt:

Another major difference is the protective surface layer. While CDs, DVDs, and HD DVDs all have 0.6mm of protective plastic above and below the actual data layer, there is a mere 0.1mm of plastic under the data layer of a Blu-Ray disc. This thinner layer means less optical losses and greater accuracy, but initially caused worries as small scratches would destroy the disc. Initial plans called for Blu-ray discs to be encased in caddies to keep them from being scratched, but the development of a cheap, effective hard coating technique by TDK, called Durabis, means that Blu-ray discs will be caddyless like current DVDs. TDK also claims that despite the thinner layer, the coating will result in increased durability over existing optical media, saying that it will stand up to being scratched by a screwdriver.

So, which standard will win out in this grudge match? Both have advantages and disadvantages. Blu-ray's goals are loftier and it dominates HD DVD on the spec sheets, with higher initial and projected capacities, data rates, and superior durability. On the other hand, HD DVD is available now, and is perfectly satisfactory for the demands of current high definition content. The decision may actually come down to gamers.