Verdict

Both are CMR drives suitable for NAS. The ST16000NM000J has the lower measured failure rate (0.22% vs 0.54% AFR), making it the safer long-term choice.

ST16000NM000J ST16000NM001G
Capacity 16 TB 16 TB
Recording tech CMR CMR
RAID / NAS safe Yes Yes
Class Enterprise Enterprise
Spindle speed 7200 RPM 7200 RPM
Cache 256 MB 256 MB
Noise (idle) - 29 dB
Fill Helium Helium
Interface SATA SATA
Failure rate (AFR) 0.22% 0.54%
Price / TB $29.69 $33.65

Highlighted cells mark the stronger spec for a NAS build. Failure rates from Backblaze Drive Stats where available; $/TB shows once live prices are wired.