HD DVD / Blu-ray Disc comparison
HD DVD competed primarily with Blu-ray Disc. Both formats were designed as successors to DVD, capable of higher quality video and audio playback, and of greater capacity when used to store video, audio, and computer data. Blu-ray and HD DVD share most of the same methods of encoding media onto disks with each other, resulting in equivalent levels of audio and visual quality, but differ in other aspects such as interactive capabilities, internet integration, usage control and enforcement, and even in the degree to which their specifications are fixed. The storage size also varies: A dual-layer HD DVD holds a maximum of 30 GB of data, while a dual-layer Blu-ray carries 50 GB.