Hey there, Sumanth_Summy.
Basically you can use whatever drive you like in a NAS enclosure as long as it fits properly and it has the required interface (SATA in most cases).
However NAS/RAID drives have specially designed firmware, which provides better performance when used in a NAS/RAID environment and the WD Red drives are tested extensively in order to be able to assure that they'll withstand a 24/7 working environment.
That doesn't mean that you can't use a regular usage drive in a NAS, I'm just saying what are some of the differences.
Please let me know if you have any questions.
Boogieman_WD