Verdict

Both are comparable SSDs. The WDS100T1R0C is rated for more write endurance than the WDS100T1R0A, so it's the longer-lasting choice for a NAS that sees steady writes; for light use either is fine and price decides.

WDS100T1R0A WDS100T1R0C
Capacity 1 TB 1 TB
Form factor 2.5 M.2
Interface SATA NVMe
NAND type TLC TLC
Endurance (TBW) 600 TB 2,000 TB
DWPD - -
DRAM cache Yes Yes
Power-loss protection No No
Sustained write - -
Price / TB $17.26 $281.97

Highlighted cells mark the stronger spec for a NAS build. Failure rates from Backblaze Drive Stats where available; $/TB uses the cheapest live price where available.