They have an upper burnable ink coating like on the bottom the laser can lighten or darken to add labels.
-Drawback is they are monochrome. You must have a lightscribe compatible optical drive. Both side of the CD must be burned taking longer.
The alternative is disks with printable top surfaces. HP came up with an ink system and optical disk top coating that can be printed to in Specially designed inkjet printers.
-Draw backs $pecial printer and $pecial media and $pecial inks.
The old way of gluing a paper label on the media has many drawbacks. Worst of all is if the label bubbles or comes loose it will destroy (shatter and come apart) the media and possibly the drive it is in. On optical disks with the "burned" layer on top the glue from the labels attacks the ink and destroys it making the disk useless.