CD, DVD, and Blu-ray are types of optical discs that are used for the permanent storage of data. They are used to store music, video, images, and other variety of data.
The main difference between the 3 types of optical discs is the storage capacity and the types of data that each disc can store. Again while the CD and DVD use red laser light to read and write data Blu-ray uses a blue laser.
Compact Disc (CD)
These are the old types of optical discs that were developed for music storage and data. They have a limited storage capacity of 750MB.
Compact Discs can be CD-R which means you write on it once and read it many times. You cannot rewrite data in these discs. The other type is CD-RW, which allows for Reading and Writing more than once.
To burn data to the disc you can use either CD, DVD, or Blu-ray drive. Most optical disk drives are backward compatible. This means a Blu-ray drive can read and write a CD but a CD drive cannot read a Blu-ray disc.
Digital Versatile Disc (DVD)
It is also known as Digital Video Disc. The DVD was designed mostly to be used for video and movie storage. It has a capacity of approximately 4.5GB for single-layer and 9GB for double-layer discs.
It is used to store standard-quality movies, pictures, and data. Just like with CDs, DVDs are either DVD-R or DVD-RW. To read and write data on DVD you require either a DVD or Blu-ray drive.
Blu-ray disc (BD)
This is the latest optical disc that was designed to store high-definition video data. It has a capacity of between 25GB to almost 100GB depending on the types that you are using. It uses blue laser light, unlike CD and DVD which uses red laser light.
To read or write data on a Blu disc you need to have a Blu-ray drive, this means the old CD/DVD drive will not work. The disc is hard coated which makes it more resistant to scratches compared to other types of optical discs.
You can read more on the characteristics, uses, and advantages of Blu-ray in this other article.
Difference between CD and DVD
The main difference between CD and DVD optical discs is the storage capacity. A standard DVD can store data of up to 4.7GB for a single layer while a CD carries 750MB. Physically the 2 discs look the same and have the same physical size.
While CDs were created for audio music DVDs were made for standard video and movie formats.
Difference between DVD and Blu-ray
The Blu-ray discs were made for High Definition videos which was an improvement to DVD. while DVD uses red laser light to read/write data Blu-ray uses a blue laser.
A DVD disc can only store a maximum of 9GB for double layer while blu-ray has a maximum of 100GB of storage.
The physical size of the 2 discs is similar but blu-ray has a hard coating which makes it more resistant to scratches.
CD vs DVD vs Blu-ray
|Storage capacity||CD storage capacity of 750MB.||Single-layer disc has a storage capacity of 4.5GB while a double layer has 9GB.||Single-layer Blu-ray disc has 25GB while a double layer has 50GB.|
|Types of laser light used||It uses red laser light to read and write data.||DVD uses red laser light to read and write data to the disc.||Blu-ray uses blue laser (blue-violet) light to read and write data.|
|Suitable types of data stored||It is suitable for music and data.||They are suitable for standard-quality video and data.||Most suitable for high-definition video. It can store HD movies with the best quality.|
|Disc drive used to read and write||It can use a CD, DVD, or Blu-ray disc drive.||It can use a DVD or Blu-ray disc drive.||The disc can only use a Blu-ray drive. If you have an old DVD drive then it means you need to get a Blu-ray drive.|
|Laser wavelength used||Use a laser wavelength of 780nm.||DVD uses a laser wavelength of 650nm.||Blu-ray uses 405nm of laser wavelength. This makes it possible to store more data within a smaller storage area.|
|Speed||It is slow to read and write data on the disc.||Relatively fast than the CD when reading and writing.||It is the fastest of the 3 types of the optical disc.|
|Cost||It is the cheapest of the 3 optical discs.||Cheaper than the Blu-ray but more expensive than the CD.||Most expensive of the 3 discs.|