Difference between DVD-R and DVD+R discs

In prior readings, and analysis that I've read, DVD-R has a GREATER compatibility than DVD+R - for example, on older DVD Players (for example, 2004 and earlier), DVD-R would work in 90% of systems whereas DVD+R would work in 80%. (These are numbers from memory and could be off, but I'm 99% certain that -R was MORE compatible than +R.)

In addition, -R has 6.625 MiB more usable space. See: http://www.videohelp.com/dvd

From About.com:

Standards Differences

1) The DVD-R (pronounced "DVD dash R") and -RW media formats are officially approved by the standards group DVD Forum. The DVD Forum was founded by Mitsubishi, Sony, Hitachi, and Time Warner, so it has tremendous industry support for its technical standards.

2) DVD+R ("DVD plus” R) and +RW formats are not approved by the DVD Forum standards group, but are instead supported by the DVD+RW Alliance. The DVD+RW Alliance is supported by Sony, Yamaha, Philips, Dell, and JP, so it also has tremendous industry support for its technical standards. Note that Sony supports both organizations.

Technical Differences

The main functional differences between DVD-R and DVD+R are:

1) the DVD recorder's built-in defects management

2) the way the recorders format and rewrite DVDs

3) the price.

My understanding is that DVD+ is the better system, especially now that virtually all drives will handle both media.

http://www.cdfreaks.com/article/203-Why-DVDRW-is-superior-to-DVD-RW/