The retail has some bonus features that have absolutely nothing to do with the inside of the drive. However, these features almost entirely offeset the price difference.
Safer packing, 80 wire cable included, and 1 blank media (marked 16--use at 12). Software includes the very reliable Record Now.
I've got to value the retail box as well because it is worthwhile to have the drive securely packed in its retail box to make it's international trip while well padded.
The retail package also includes a direct relationship with BenQ for the next year and extreme ease of updating the firmware.
So, if you're purchasing one or two drives, you will notice no eventual difference in price by going with the retail model--and you will have greater convenience.
The 1620 Pro combines slight additional fine tuning of the hardware with no differences in construction or parts list when compared with other products of the same manufacture date. This makes no sense to me either.
Any differences between this and a 1620 have been undetectable by end-users.
Speaking of differences, even drives going down the same conveyor belt will be all marginally different than their neighbors. This is true of all optical products of any sort. The differences are all extremely slight because BenQ has great quality control.
Certainly feel free to purchase any of the BenQ products.
BenQ does very well (equally well) with their quality control on both OEM and retail.
New 1620's and the 1620 Pro have been appearing with a label that indicates a larger load for the 5 volt channel of your computer's power supply. As usual for any computer system, one should have a nice strong name-brand power supply to achieve ideal results from any of the components.
As a CNE and certified service tech, I would like to take a moment to thank ThermalTake and Antec for making quality power supplies that easily improve enthusiast's computers. Ask yourself if your computer is an "office spec" or if it is packed full of goodies? So when purchasing any new and additional component for your computer, spare a second to take a look at the most important and most ignored component--while you've got the computer open anyway.
Don't worry, though--BenQ is an extremely tolerant, well designed computer product that works well in almost any situation.
For an analogy, my cat will eat anything (even mass quantities of toilet paper), but I feed him Purina.
P.S. There are 9 versions, and they all will accept the same firmware (which indicates all=same thing). With so little differences, go with your favored choice of most supportive vendor combined with longest product warranty, and other valued features that have nothing whatsoever to do with 9 identical optical drives.