With the introduction of the X18 platform, Seagate introduced a new part number for 16TB Exos drives - ST16000NM000J. It's not much different than the X16 ST16000NM001G
The similarity between 16000NM001G and 16000NM000J
Both have the same workload (550TB per year), reliability (2.5 million hours MTBF), warranty (5 years limited), and of course the same capacity.
Difference between 16000NM001G and 16000NM000J
First, they are based on a different platform.
ST16000NM001G is on the X16 platform (the highest capacity on X16). It has 9 disks with 18 heads, each disk about 1.8TB.
ST16000NM000J is based on the X18 platform, which has 18TB as the highest capacity. It also has 9 disks with 17 heads, each disk about 2.0TB. So this is the same as an 18TB drive, just with 1 headless.
Secondly, the ST16000NM000J has a slightly higher data transfer rate ( 258MB/s) compared to the ST16000NM001G ( 249 MB /s) due to the higher density.
At the distribution level, the prices seem to be the same for both. Practically, both are almost identical drives, and aside from a slightly better transfer rate, there is no difference. If you are thinking about it, you should go for whatever part number is available.