Those model numbers seem to be the HP part numbers. Don't HP rebadge drives from other vendors?

If so, then it would probably be useful to see if the vendor drive model numbers are available.

For the dramatic increase in iops, I wonder if there are more head+actuator assemblies on the newer drives or similar? Along the lines of these:

https://www.seagate.com/innovation/multi-actuator-hard-drive...