One main advantage of NAS specific hard drives is that they "give up" trying to read much faster when a bad sector is detected. Standard consumer drives assume a bad sector is the only location of that data piece, so try multiple times in many different ways to read it successfully. However, enterprise or NAS drives in general are part of some sort of redundant array (RAID, ZFS, etc.), and if a sector on one disk goes bad, it's not a big deal, so it quickly marks the sector as bad and rebuilds it from other data. This doesn't slow down the whole array much, and the RAID logic won't mark the whole drive as bad, whereas with a consumer drive the slow down on read time may get the whole drive marked as bad. As Presjar says, the warranty is also part of the cost difference. FWIW though, I've been using WD Green drives without any troubles in RAID array for several years. If super high uptime requirements aren't necessary, you can just tell the RAID controller to have a longer timeout on marking a drive bad, and get away from the problem mentioned earlier.