Sony RDR-GX7 - Manual (Page 7)

Write-once DVDs can only be recorded once, like photographic film. Rewritable DVDs can be recorded and re-recorded many times, like tape.
Each type has its own advantages, and is chosen depending upon the type of use.
7
There are write-once and rewritable DVDs
Write-once
DVD-RW, DVD+RW
DVD-R and DVD+R are "write once" discs,
meaning they can only be recorded once. Since phase change is not permanent, DVD-RW, DVD+RW and
DVD-RAM allow data to be written and rewritten over and over.
Merit
There is no danger or mistakenly erasing or
recording over the recorded content.
Rewritable
DVD-R , DVD+R
This type is used for DVD-video
and other playback uses. Data is
represented by the presence or
absence of a pit in the pit lanes
pressed on the disc.
Pit
Read-only
DVD-RAM DVD-ROM
Organic dye
(groove
recording)
Track pitch: 0.74 microns
Phase
change
material
(groove
recording) Phase
change
material
(land &
groove
recording)
What is the difference between
DVD-R and DVD+R?
While DVD-R and DVD+R both have the
same basic construction as DVD-ROM,
there are differences in their rotational
control systems and data recording
positions.
What are the differences between DVD-RW,
DVD+RW and DVD-RAM?
While DVD-RW and DVD+RW both have the same basic construction and
performance of DVD-ROM, there are differences in the way their disc
rotational control systems and data recording positions are configured.
DVD-RAM uses a special land and groove recording configuration and
specification which enables data to be rewritten up to 100,000 times,
compared to 1,000 times for DVD-RW and DVD+RW.
Merit
The same disc can be used over and over.
Unwanted sections of the disc can be erased and
rewritten.
Track pitch: 0.74 microns Track pitch: 0.615 microns
Differences in
writable DVD
1
Track pitch: 0.74 microns
Physical format
groove land