Optical drives have microscopic bumps that are read by laser beams.
When you burn data to a disc, it’s not creating bumps. Rather it is darkening certain areas of the disc that have photosensitive dye in them.
CD-ROM/CD-RW
CR-ROM stands for Compact Disc ROM. CD-ROM have 700 megabyte (MB) capacities.
CR-RW stands for Compatc Disc ReWritable.
DVD-ROM/DVD-RW/DVD-RW DL
DVD-ROM stands for Digital Versatile Disc.
DVD-ROM can hold 4.7 GB on a single layer. If the DVD allows for writing to both sides of the disc, then it can hold up to 8.5GB for dual-layer.
DVD-RW is DVD Read and Rewritable.
DVD-R DL stands for Dual Layer.
Blu-ray
Blu-ray is so called because it uses a blue-violet laser to read discs (DVD uses a red laser). The blue laser, in conjunction with a special lens, allows the laser to be more focuses with provides for higher density data storage.
Single layer Blu-ray Discs can hold 25 GB. Dual layer can hold 50 GB.
BD-R
BD-R stands for Blu-ray Disc Recordable
BD-RE
BD-RE stands for Blu-Ray Disc Recordable Erasable.
