Blu-ray Disc Vs. HD DVD

The competing Blu-ray Disc and HD DVD formats aren't entirely dissimilar. Their differences, however, are significant. Blu-ray supports higher-capacity discs, which gives the format more headroom to mature. Blu-ray's additional space also allows movie studios to provide full, uncompressed audio (called Linear PCM) rather than solely compressed (but high-bit-rate) lossless audio technologies, such as Dolby TrueHD and DTS-HD Master Audio.

Where the Blu-ray Disc format falters today is in how much interactivity it can deliver in the movie playback experience. The new world of interactivity includes such features as on-demand picture-in-picture displays, the ability to bookmark favorite scenes, Java-based games, and extra content that you can download to your player directly (such as supplemental audio tracks, featurettes, or trailers) via ethernet. Though interactivity is a big part of the Blu-ray specification, the spec inexplicably failed to require early Blu-ray Disc players to have the minimum hardware needed to enable such features. Players produced after October 2007 will fix this problem by adding a 256MB minimum requirement for storage and a secondary video decoder (for on-demand picture-in-picture video).
The HD DVD format, by contrast, specified more-stringent minimum requirements from the outset. All HD DVD players must have an ethernet connection, a secondary video decoder, and at least 128MB of built-in storage.

These minimum specs enable all current HD DVD players to support the format's fun interactive features, giving you the ability to create bookmarks held in memory, even after you eject a disc; to play a secondary video stream (for viewing discs mastered with picture-in-picture extras that you can switch on and off while watching the movie); to customize your viewing experience (by changing the color of a car on screen, for example); and to download firmware updates and additional content (such as trailers or extra features that will eventually be stored on remote servers).

The catch is, these features are not available on all movie titles (see "Now Playing on Blu-ray and HD DVD" for details on what studios are doing on their movie discs). In fact, no HD DVD movie title today takes advantage of the ethernet connection the format requires players to have.

Dueling technical specs aside, Blu-ray for now appears to be a better gamble than HD DVD, if only for the greater number of movie studios supporting the format. For flicks such as Cars, Casino Royale, Eragon, and the Pirates of the Caribbean Series, you'll need Blu-ray, since those films are produced by studios in the Blu-ray camp. But King Kong, Lost in Translation, Midnight Run, and Serenity, for example, are HD DVD only.

Source:
Melissa J. Perenson