Blu-ray BD-R Discs
Blu-ray writeable discs are one of the highest-capacity optical disc storage options on the market. The label BD-R refers to the fact that the discs are writeable. There are discs that are also re-writeable and they come under the label BD-RE.Storage Capacity
Blank Blu-ray discs come in several different storage capacities. They have a 25 GB capacity per data layer, so a 25 GB blank Blu-ray BD-R disc is composed of a single layer. A 50 GB blank Blu-ray BD-R disc has two layers. Discs that have greater capacity than 50 GB are in a different category, which is BDXL.Disc Quality
Blu-ray discs comes in two quality levels: HTL and LTH. HTL, or high to low, quality discs use inorganic material for the recording layers. This means the disc is less susceptible to light and other ageing factors. It also means it is compatible with more disc burners and Blu-ray players. LTH, or low to high, uses an organic dye to create layers on the Blu-ray disc. The dye is very sensitive to light and the data written on an LTH disc will degrade faster than HTL discs.BDXL
Blu-ray writeable and rewriteable discs that are greater than 50 GB require a special machine called BDXL. These machines are able to write discs on three and four layers. If you're looking for blank Blu-ray discs in sizes larger than 50 GB, make sure that you have a BDXL-compatible machine. Also, keep in mind that another format has been approved, one that will allow a double-sided triple-layer disc of 200 GB.BD-RE
If you are interested in being able to re-write over a Blu-ray disc, BD-RE discs are also available. BD-RE discs need to be formatted before being written over again, but in theory, they can be written over forever. You can find BD-RE discs in single-, dual- and triple-layer formats. As with BD-R, triple layers must be used in BDXL machines only.