What specifically is the difference between DVD+R disks and DVD-R disks?

They are actually different formats,. which require different equipment to record on. Eg Pioneer's are a DVD-R/RW format. HP/Sony has come up with a different recording system, the DVD+R/RW system, and then off course there is the DVD-RAM system... All of these 3 are supposed to be able to play back on any DVD machine, but when you want to record a disc, you have the make sure the DVD-recorder you have, and the disc are the same format. You cannot put a +RW disc in a -RW machine - it won't record.

dvd+r lets you write on multiple levels on the disk and is used by specific companies/manufactures. DVD-r only writes on one level. Think of it like video games: PS1 games were good but the graphics werent all that great and the levels kinda small compared to the PS2 games which are more detailed and have longer levels and games. IT takes a specific laser to write multiple layers on dvd+r disks. Normally any DVD/CD player can write onto a dvd-r disk.

DVD+ is considered to be better engineered. Just like other + type formats, it's less susceptible to errors and has better tracking and speed control. - formats are still a good option for recording data. DVD+/- are better than CD+/Rs because they can hold more data. 4.7 Gigs compared to 700 MB; Big difference! DVD DL (Dual-Layer) can hold up to 8 Gigs. DVD DLs write to more than one layer on the DVD. Hope this helps. : )