A DVD and a Blu-ray disc has about the same thickness although the DVD is made up of two polycarbonate layers while the Blu-ray disc is made up of a thicker single layer. The DVD sandwiches its data between its two layers while a Blu-ray disc provides for the placement of data on top which prevents readability problems associated with DVDs.

The occurrence of a DVD surface that is not exactly flat and therefore not perpendicular to the beam can result to a disc tilt which distorts the laser beam. This problem is virtually eliminated in the Blu-ray disc since the recording layer sits closer to the objective lens of the reading mechanism. Both are built by injection molding although the Blu-ray discs are done at a reduced cost because of the use of a single disc which need not be glued together.