Verdict

Both are CMR drives suitable for NAS. The ST12000NM001G has the lower measured failure rate (0.96% vs 2.97% AFR), making it the safer long-term choice.

HUH721212ALE604 ST12000NM001G
Capacity 12 TB 12 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) 20 dB 29 dB
Fill Helium Helium
Interface SATA SATA
Failure rate (AFR) 2.97% 0.96%
Price / TB $33.87 $39.71

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.