What is it with dual layer/double layer....all the damn covers say double layer, so which ones are truly dual layer...i bought memorex, sony, verbatim and all have failed me for 360 .dvd burns...I thought they were all dual layer, but the sony for sure was a double layer...no cases ACTUALLY SAY DUAL LAYER..what a bitch
DVD+R DL is known as "double-layer" to distinguish themselves from "dual-format" drives. DVD-R DL is identified as "dual-layer." There is no reason for this except to be different. It confuses customers, as does the fact that double-layer discs are relatively well supported by drive manufacturers while dual-layer discs are not.
Both versions are designed the same way (not accounting for their format differences), with two different methods of manufacturing. The first version was the double polymer method ("2P") that used a temporary photo-polymer layer as a stamper that was used for the inner layer, cured by UV rays, then peeled off and thrown away. The newer, less expensive method is the inverse stack ("IS") method that creates an upper substrate half molded "upside down." This method is less expensive, faster, and freer of contaminants; but it is reserved for 8X discs so that only the newest drives can record on them.
Retailers, in their stupidity and ignorance, have put only 8X DL discs on their shelves instead of keeping the more compatible 4X 2P DL discs as well as the newer 8X IS DL discs in stock. That means that unless one has purchased a recent drive with a power supply, firmware, and a laser diode that support 8X DL recording, recording on DL discs is very likely to run into failure.
