Making sense of CDs and DVDs: What’s the difference?

We all have them CDs and DVDs, but what is the difference between them? What they have in common is that they are both about the same and size shape, and look about the same and both hold information of some sort. One of the first differences (and most easily understood) is that DVDs can hold at least seven times as much information as CDs. This is accomplished by using multiple recording layers and even recording on both sides of the media. Your information is saved in a series of bumps and holes (called pits). DVD technology writes and reads smaller pits than CD technology. With the smaller pits it is possible to record more pits in a track and also possible to write more tracks per disk. DVDs with higher storage capacity will have more tracks than similar DVDs with less capacity. The narrower tracks require special lasers for both reading and writing. That explains why DVD players can’t play CDs and CD players can’t play DVDs. This problem is solved by putting two lasers in drives (one for reading CDs and the other for DVDs).

Recording format is another big difference between DVDs and CDs. DVD recording uses UDF (Universal Data Format). This format allows us to save data, video, audio or a combination of the three in the same file structure. CDs do not comply with UDF.

Making sense of + x and – on your CD and DVD.

This month we make sense of the information that follows CD and DVD.

R vs. RW:
The “R” stands for recordable while RW stands for re-writeable. On recordable disks you can record information on it until it is full, but can’t erase and re-write on the disk. The re-writeable disks work more like our old floppies that you could copy to, erase and reuse. In general, we suggest that you choose “R” for archiving files (things you don’t want to change) and choose “RW” for files that are changing and for temporary backup.

– vs +:
The “-” (minus) and the “+” (plus) signs identify two different formats that are not compatible with each other. To clarify: a DVD-R/DVD-RW writer can only write to a DVD-R/DVD-RW disk, while a DVD+R/DVD+RW writer can only write to DVD+R/DVD+RW disks. These formats do not affect the storage capacity of the disk. If you have a Combo drive then you are in luck, as you can use either format. All of the kiosks at Leave A Legacy are equipped with Combo drives.
The next question is: “How do I know what kind of disk I have?” The writers and players will often have a logo sticker on the front or back that tell which kind you have. You may need to get out a magnifying glass to read it if your vision is not stellar.

The “x” on your disk, simply put, is an expression with a number following that tells you how fast you can record to the disk. The difficulty comes in when you compare CDs with DVDs, since DVDs are so much faster they use a different unit of measure to express their speed. The 1x of a DVD is equivalent to 8x of a CD.