It is difficult to distinguish between DVD and Blu-ray from mere physical appearance, as both looks kind of same in terms of size and shape. But the two items have their distinct characteristics and comes in different features. They differ in storage capacity, disc construction, laser technology, player compatibility and image resolution.
Storage capacity is usually measured in GB or gigabytes. A single layer DVD can store around 4.7 GB, which are normally called DVD-5s. The double layer DVDs or DVD-9s, can hold up to 8.7 GB worth of data. However, a single layer Blu-ray disc can store around 25 GB data, whereas the double layer Blu-ray discs can hold up to 50 GB. So Blu-ray is definitely better than that DVD in case of storing information.
As mentioned before, physically both the items are identical, with grooves/pits in the bottom layer for facilitating laser rays to read the preserved data. However, the distance between the grooves are closer to HD 3D Printers for Blu-ray than for DVD, inhibits the storage capacity of DVD.Another physical distinction appears in the way the data are protected from external shock. The protective layer used in Blu-ray is thinner but it contains a hard coating, making it more resistant to scratch.There are also distinctions between the items in terms of laser technology. The laser used in DVDs is red, and as the name suggests, it is blue in case of Blu-ray. The shorter wavelengths enable more precise interpretation of data stored in Blu-ray discs.
The technological shift may have made our lifestyle smooth, but at times it gets difficult to adjust with the rapid transition. The switch from VHS to DVD format happened not quite long ago, and now we are there are Blu-ray players and discs in the market. The DVD players cannot play Blu-ray discs because of the red laser used for reading. Blu-ray players can play DVDs but it will not offer HD quality like blu-raydiscs.
DVDs also fall behind Blu-ray discs as the later can facilitate image with higher resolution. Most of the DVDs have a default resolution of 480 pixels or enhanced resolutions of 520 pixels. So when DVDs are accommodated in big screen the image display seems grainy. The DVDs can store high definition images but the duration of playing then gets shortened. A Blu-ray disc has no such complexity as it was designed to facilitate high resolution image. At present it can offer the best image resolution in comparison with all other available devices, as not even satellite companies or HD cable can display images in 1080 resolution yet.
It is true that Blu-ray discs outplay DVDs in all aspects, but DVD players will not simply disappear from the market; thanks to their widespread popularity in the past when most households had one bought to entertain them. As DVD players cannot open Blu-ray discs, the consumption of DVDs will not shrink right way. But Blu-ray discs, with more storage facility and improved image quality, are definitely better than DVDs.