DVD 5 is known to be a single-layer disc. This will be able to store a lot of bytes of approximately around 4,700,000,000 bytes. This will be equal to more than 4GB on your device. If you would like to use the DVD5 to store movies, this is possible, but you can only store movies that are about 120 minutes or 2 hours long.
DVD 9 is going to be a bit different. This will store more bytes. It can store approximately 8,450,000,000 bytes, which means that it will be able to provide more space when you place it on your computer.
This can store a movie that is about 240 minutes long. If you have short movies, it can store more than one movie.