The most important consideration when discussing these formats is that they are not compatible. This means that Blu-Ray players will not play HD-DVD discs, and HD-DVD players won't play Blu-Ray discs. However, both players will be backward compatible.

DVD and Blu-Ray is both high-definition formats and use blue-laser technology. Both technologies have reduced the width of the laser beam that reads a disc to 405 nanometers. The blue-violet laser used by both formats has a shorter wavelength than the red laser used in today's standard DVD drives. This allows more information to be packed onto a disc.

The introductory HD-DVD discs hold 15 GB per side, but Blu-Ray Discs have a higher capacity holding 25 GB per side, and 50 GB for dual layer discs. Blu-Ray is working on a quad layer prototype that will hold 100 GB, while HD-DVD is said to be toying with a triple layer that holds up to 45GB.

Both HD DVD and Blu-ray discs deliver crisp, clear pictures and sound, a perfect match for the high-definition TVs sets that Americans have been rushing to buy for the past two years. Blu-ray is the successor to DVD. The standard was developed collaboratively by Samsung, Sharp, Sony, and Thomson. It became the default optical disk standard for HD content and optical data storage after winning a format war with HD-DVD, the format promoted by Toshiba and NEC.

The blue laser reads from and writes to the disc rather than the red laser of DVD players. The blue laser has a 405 nanometer wavelength that can focus more tightly than the red lasers used for writable DVD. Like the rewritable DVD formats, Blu-ray uses phase change technology to enable repeated writing to the disc. But HD DVD players are also able to connect to the Internet to download trailers and other bonus content for discs, and can have a director or actor provide commentary in a small window while the movie plays.

Blu-ray's standard storage capacity is enough to store a continuous backup copy of most people's hard drives on a single disc. Single-sided Blu-ray discs can store up to 13 hours of standard video data, compared to single-sided DVD's 133 minutes.

Blu-ray also features data streams at 36 megabytes per second, fast enough for high quality video recording. For more details http://www.av-setup.com