Difference? LG GSA-5160D vs LG GSA-5163D

Quick question… I tried finding an answer, but was unable to find it.

Simple/stupid question:

What is the diffreence between the two models? Is there a benefit to one model vs. the other? Thanks.
LG GSA-5160D vs LG GSA-5163D

Get 5163D instead of 5160D.

GSA-5163D = external version of GSA-4163B
GSA-5160D = external version of GSA-4160B

GSA-4163/5163 is the only true 16x DVD writer from Hitachi-LG (HLDS.) Though GSA-4160/5160 also writes at 16x to DVD disks, it uses Zone CLV and only writes at 16x to DVD+R disks.