Blu-ray discs and DVDs may look similar, but there's a world of difference between the two. As the first widely available high-definition home video format, Blu-ray allows viewers to see movies, hear and experience movies in ways that DVD never could. DVD may be superior to VHS, but when compared with Blu-ray, it's vastly inferior in almost every way.
The biggest difference between Blu-ray and DVD is space. While a dual-layer DVD holds about 8.5GB of information, a Blu-ray disc can hold up to 50GB. This translates to more content, a clearer picture and better audio.
Blu-ray is the first massively available high-definition media format. While DVDs have far better picture quality and clarity than VHS, the format is still limited to a resolution of 720x480. Blu-ray resolution can be as high as 1,920x1,080. Also, Blu-ray is a progressive scan format, meaning the entire image is projected in each frame. DVDs are an interlaced format, meaning that individual frames project alternating lines of video. Progressive scan images are clearer and sharper than interlaced images.
Blu-ray's extensive storage capabilities mean that it can store lossless, or uncompressed, audio. All other digital audio formats, including DVD, are compressed in some way, which can result in lesser audio quality. Lossless digital audio can sound as good as, or even better than, the audio in a theater. Blu-ray also supports newer audio codecs, including Dolby TrueHD and DTS HD.
The added space that gives Blu-ray better picture quality and better audio quality also gives the medium added space for extra bonus features. More commentary tracks, deleted scenes, behind-the-scenes footage and more are possible with the extra space. Unlike DVD players, Blu-ray players can be connected to the Internet as well, allowing for Internet-enhanced content.
Right now Blu-rays cost more than DVDs and its not clear if that gap will ever be bridged, although its safe to assume that as the medium becomes standard so will budget titles.
Blu-rays take longer than DVDs to load, sometimes taking over a minute to start after they are put in the player. This has improved over time and the load times may decrease further as Blu-ray players become more advanced.
- a dvd-r disc image by wayne ruston from Fotolia.com