What is the difference between DVD-r and DVD r and which does the industry use?
The formats are DVD-R and DVD+R (Plus DVD-RW, DVD+RW, and
DVD-RAM, DVD-ROM)
(Stolen from Answerbag)
DVD+R is a DVD disc that allows multiple layers for one disc
where as DVD-r only allows one layer. They will not compete to
become the de Facto standard, because they are both here to stay.
Multi layer DVD+R can allow extra capacity per disc than DVD-R
hence its high cost!
(Not stolen from Answerbag, but some technical site)
DVD+R is a write-once format intended to be more compatible with
more DVD players, though at this point it seems to be about even
with DVD-R, which remains the most compatible computer-burned DVD
format.
The plus formats have the same data storage capacity as the
minus formats (4.7GB)...
(Wikipedia)
...But In October of 2003, it was demonstrated that double layer
technology could be used with a DVD+R disc to nearly double the
capacity to 8.5 GB per disc. Manufacturers have incorporated this
technology into commercial devices since mid-2004 (DVD+R DL).