HD DVD
Short for High Definition Digital Versatile Disc, HD DVD is a high definition DVD standard jointly developed by NEC and Toshiba as a replacement for DVD. The first HD DVD player was released by Toshiba in Japan on March 31, 2006 and later an HD DVD player in a computer with its release of the Toshiba Qosmio 35 on May 16, 2006. HD DVD discs are capable of holding 15 GB per layer, which is almost three times more than the traditional DVD that is only able to hold 4.7GB.
HD DVD was backed by Intel, Microsoft, RCA, Sanyo, and Toshiba and had been in a format war with Blu-ray until February 19, 2008 when Toshiba officially announced it will no longer manufacturer HD DVD players or discs.
BD
Short for Blu-ray Disc, BD or BD-ROM, is an optical disc jointly developed by thirteen consumer electronics and PC companies such as Dell, Hitachi, Hewlett Packard, LG, Mitsubishi, Panasonic, Sony, and TDK. The Blu-ray was first announced and introduced at the 2006 CES on January 4, 2006 and is capable of storing up to 25 GB on a single-layer disc and 50 GB on a dual-layer disc, each disc being the same size as a standard CD. The picture shows a blue laser in a Blu-ray disc player.