[wtallis]

There really isn't much diversity in NAND flash product lines. Each generation of 3D NAND from WD+Kioxia basically consists of two sizes of TLC die and one or two sizes of QLC die. For the purposes of this conversation, binning doesn't matter because "SSD grade" is already the top bin. So the only variable on the NAND side for a high-end 2TB drive is the question of whether it's built with the high-capacity die (cheaper per GB), or twice as many of the low-capacity dies (potentially faster if it allows more controller channels to be fully populated, but that's usually not a problem at 2TB).

[Retric]

I’m not sure what you mean by SSD grade, Grade A to D chips aren’t strictly about binning but also traceability/fraud.

One hardware guy mentioned internal defects can cause differences is the amount of reserve sectors that a final product ends up with. That’s exactly the kind of arbitrary cutoff that lets companies charge different prices for the same part.

[wtallis]

SSD-grade is the term used for flash with a low initial defect rate. See eg. https://www.szyunze.com/wp-content/uploads/2023/08/SpecTek-N... (from https://www.szyunze.com/spectek-unveiling-truths-about-degra... )

Lower-grade flash with higher initial defect rates is what gets used in USB flash drives and SD cards, and some bargain-bin SSDs with lower usable capacities (ie. 960GB rather than 1TB).

The stuff used in a WD Black or WD Blue branded consumer SSD is not a different quality grade from the stuff used in any other mainstream consumer SSD, Apple's included.