What is D5 and D9? What is the difference? Any other formats?

There are 4 standard formats. D10 and D18 are not as common.

A DVD-5 (single sided) DVD-Video disc will hold nominally 133 minutes of high quality MPEG-2 encoded video, together with three surround-sound audio channels and four subtitle channels. (Without video compression one DVD-5 disc would hold only about 3 minutes of video).

A DVD-9 (dual layer) disc increases the playing time to 240 minutes of continuous video.

A DVD-10 (double sided) disc will hold a nominal 133 minutes on each side (ie 266 minutes in all), but the disc needs to be turned over to play the other side.

A DVD-18 (dual layer, doubled sided) disc can hold 240 minutes on each side and the disc also needs to be turned over to play the other side.

Most DVD is D9 or D5 format. DVD-Cloner can clone D9 to just ONE DVDr/rw disc (D5 format) without evident losing.