The truth is that the two competing technologies use different
formats. No single company "owns" DVD and both technologies have
their "champions".
DVD-R/RW was developed by Pioneer. Based on CD-RW technology, it
uses a similar pitch of the helix, mark length of the 'burn' for
data, and rotation control. DVD-R/RW is supported by the DVD Forum,
an industry-wide group of hardware and software developers, and
computer peripheral manufacturers. The DVD-R format has been
standardized in ECMA-279 by the Forum, but this is a private
standard, not an 'industry' ISO standard like the CD-R/RW Red Book
or Orange Book standard.
DVD+R/RW is also based on CD-RW technology. DVD+R/RW is supported
by Sony, Philips, HP, Dell, Ricoh, Yamaha, and others, and has
recently been endorsed by Microsoft. DVD+R/RW is not supported by
the DVD Forum, but the Forum has no power to set industry
standards, so it becomes a market-driven issue.
http://www.videohelp.com/dvd