While many people have seen the difference visually and heard the difference audibly between Blu ray discs and HD DVDs, others, most of whom still have DVD players, wonder what makes the Blu Ray discs the best. There are actually several differences between these two formats; many more than what most people realize. There had been a format war that raged between Sonys Blu Ray and Toshibas HD DVD, but when Warner Bros. stopped supporting the digital disc format and went to Blu Ray, it was Sony that prevailed. Toshiba then announced that it was discontinuing all manufacturing of HD DVD products.



The first category of differences between the two formats involves codecs. For the most part, both formats have the same codecs: both have MPEG 2, Microsoft Video Codec 1, Dolby Digital AC 3, DTS, and linear PCM. However, the HD DVD also has Dolby Digital EX, Dolby Digital Plus, and Dolby TrueHD with DTS HD being optional. The Blu ray disc makes optional Dolby Digital Plus, Dolby TrueHD, and DTS HD.

Capacity is the category that has the most obvious differences between them, and this is where the Blu Ray disc (BD) really out does the HD DVD (digital disc). While the digital disc has a single layer data capability of 15GB and a dual layer capability of 30GB, the ROM (single layer) of the BD is 23.3/25GB and the ROM dual layer holds 46.6/50GB of data. The highest possible amount currently that has been tested as held on a BD was 100GB, and BDs have a theoretical limit of 200GB. The HD DVDs have been tested at 45GB, with a theoretical limit of 60GB.

As far as security goes, there are a few differences here as well. While BDs have BD+ dynamic crypto for the physical layer, HD DVD has only a volume identifier. Both formats also use a mandatory HDCP encrypted output and Advanced Access Content System, but the BDs also have ROM Mark watermarking technology as well.

The final differences lay in the movie studios that support each format. Three large studios use HD DVD format, while twelve use the Blu Ray format. Supporting studios for the digital discs are Dreamworks, Universal Studios, and Paramount Pictures. The twelve movie studios that support the Blu ray format are Buena Vista Home Entertainment, Hollywood Pictures, Lions Gate, 20th Century Fox, MGM Studios, Miramax Entertainment, Sony Pictures Entertainment, The Walt Disney Company, New Line Cinema, Touchstone Entertainment, Vivendi Universal Games, and Warner Bros. There are many differences between these two digital formats, and many conclude, including most of the movie studios, that it is Blu Ray, not HD DVD, that is best.