I believe that the numbers describe the DVD drive's Read/Write speeds.
The "SATA" also states what computer bus interface it uses to connect to mass storage devices, instead of IEEE, PATA, SAS, SCSI or USB. -Don't quote me on that xD
Also, the DVD drive is just a form of Optical Disc Drive that can accept both CDs and DVDs. Blu-ray is another type of Optical Disc Drive.
Sorry for not being a whole deal of help!