In this post, Chris Evans breaks down the differences between Persistent Memory and Storage Class Memory. The former puts non-volatile media directly in the DIMM slot, providing storage with extremely low latency, but requiring changes to BIOS and OS to address properly. The latter uses NAND and DRAM in a tiered system to effectively increase the addressable memory to the system. An example being Storage Field Day presenter Diablo Technologies. Of course, thanks to marketing, these terms are often interchangeable, but the article does a good job making the technical distinction clear.
