NAS drives have a feature called TLER or time limited error recovery that gives them more time to recover data in the event that an error does occur during a data transfer.
Most normal hard drives, Western Digital Blue/Black, don't have TLER.
Western Digital Red, Red Pro and Gold do have TLER.
For a raid like raid 1 normal drives are fine because if an error does occur you have a known good copy just waiting to replace it.
For a raid 5 or raid 6 you definitely want to use a drive with TLER, although nothing stops you from using WD Blue if you like to live dangerously.