What is the difference between d5 and d9 dvds?

DVD-5 (Single Side Single Layer)

D5 holds around 4 700 000 000 bytes and that is 4.37 computer GB where 1 kbyte is 1024 bytes*. DVD+R/DVD+RW and DVD-R/DVD-RW support this format. This is the most common DVD Media, often called 4.7 GB Media.

D9 holds around 8 540 000 000 bytes and that is 7.95 computer GB. DVD+R support this format. This media is called DVD+R9, DVD+R DL or 8.5 GB Media. A DVD-9 (dual layer) disc and hold 240 minutes of continuous video.

From above we can know the most important difference between DVD9 and DVD5 is capacity, the capacity of DVD9 is twice as DVD5, and many wonderful DVD movies are DVD9 format. But now why we need to compress DVD9 movies to DVD5?

First, DVD5 is cheaper than DVD9. If you want to make more copies of your favorite DVD movies, you'd better choose DVD5 disc to backup, it will save a lot of money.

Second, also another important thing: D5 is reusable and environmentally friendly disc.
You can see the disc you bought, which always display DVD-RW, DVD-R, etc. on their covers. A DVD-R is a write-once format, once you've burned the data onto that DVD platter, the disk is forever frozen with that information. Add the "W" to that, and you'll find that DVD-RW can be erased or rewritten up to a thousand times. In a similar way, the DVD+RW is defined as "DVD ReWritable" and DVD+R is defined as "DVD Recordable".

The DVD-RW and DVD+RW we always see at the market are DVD5 disc, it means that if you want to rewrite your DVD disc, you should choose DVD5 disc to backup your DVD Movies and data, you can reuse your DVD5 disc to backup different movies or data, such as write, erase, write, erase, again and again.