DVD and Blu-ray™ are two types of optical storage discs, commonly used for storing movies and other video. Although the discs look similar, there are significant differences. The difference between a DVD player and a Blu-ray™ player is the laser technology that's used to record and play back the data. A Blu-ray™ player can play most DVDs; however, a DVD player cannot play Blu-ray™ discs.
DVDs
Digital Video Discs (DVDs) were developed in the 1990s, and came to market in the second half of the decade. Information is written to a DVD with a 650 nanometer (nm) red laser, which creates microscopic bumps in a groove on the disc. A DVD player contains a laser which can read the bumps in the spiral track of data. The most common type of disc can hold 4.7 GB of data.
The quality of audio and video recorded on a DVD is very high; in most cases, video is encoded in MPEG-2 format, which offers high definition, 720 pixel resolution. Surround sound options are also often available. Many DVDs also include interactive menus, additional audio tracks, and other special features.
Blu-ray™
The Blu-ray™ player was introduced in 2006. Information is written on a Blu-ray Disc™ with a 405 nm blue laser — giving the technology its name. This laser produces a tightly focused beam, and is capable of burning more data than a red laser into the same size space; a standard Blu-ray Disc™ can hold 50 GB. Commercial audio and video is typically encoded in a proprietary format called Blu-ray Disc Movie (BDMV), although there are other formats.
The quality of the video on Blu-ray™ is higher than that on a DVD; in most cases, the resolution is 1080p. In addition, the way the video is compressed on the disc is better, which contributes to a better image. The quality of the audio on Blu-ray™ is essentially studio-quality. Like DVDs, Blu-ray Discs™ usually include interactive menus, multiple audio tracks, and other special features. This features are often more advanced than DVDs can offer, and include things like pop-up menus and picture-in-picture commentary.
HD DVD
A successor to the standard DVD, called HD DVD, was developed in the 2000s. This format could hold 15 GB on a single layer disc, and — like Blu-ray™ — used a blue laser to encode information. It also featured interactive content, very high quality audio, and video resolution up to 1080p. After a brief period of competition with Blu-ray™, however, the format was discontinued in 2008.
DVD vs. Blu-ray™
In terms of quality, Blu-ray™ can produce higher resolution video and higher quality audio than DVD. It also offers more special and interactive features. If linked to the Internet, a Blu-ray™ player can also be upgraded, and allow the user to download extras and connect to online audio and video services.
To get the most out of Blu-ray™, a consumer really needs a high definition television (HDTV) capable of displaying 1080p video, an excellent speaker system, and an Internet connection. Although HDTV has become very popular, many people still own standard definition televisions that cannot display Blu-ray™ at its best. All of this technology is also relatively expensive, although prices are dropping.
DVDs became very popular very quickly, and as a result, players and discs are found in a majority of homes in the US and other nations. As a result, it's unlikely that DVDs will simply disappear in the same way that HD DVDs did. Most Blu-ray™ players can also play DVDs, so someone looking for a new machine will still be able to play his or her older discs. DVD players cannot play Blu-ray™ titles, making them a less attractive choice for many buyers.