Samsung claims that its upcoming vertically-stacked NAND (or V-NAND) for SATA-based SSDs confers improved read- and write-speeds on the resulting drives. They are composed of 100 or more layers of stacked flash cells, whereas previous generations had 99 or less. This increased scale is the new 3D memory's main advantage over its predecessors.
https://www.notebookcheck.net/Samsung-s-6th-gen-3D-V-NAND-SSDs-have-a-groundbreaking-design-for-faster-256Gb-data-transfers.428807.0.html