We raided Newegg to get a breakdown of features side by side. For this comparison, we're focusing on the largest capacity size, 4TB. Both companies offer smaller capacity sizes as well, but the 4TB capacity size offers the best capacity per dollar.
Newegg didn't list the RPM for either drive. WD hides platter speed behind IntelliPower, but the Red operates at 5,400 RPM. The Seagate NAS spins the platter at 5,900 RPMs.
From a price standpoint, both products are between $210 and $220, depending on your e-tailer preference. Newegg shows the WD Red 4TB at $209.99 and the Seagate NAS at $219.99, at the time of writing.
We found the WD Red 4TB for as low as $198 with Google Shopping and the Seagate NAS 4TB is $199.92 at B&H. That puts both drives on equal footing when it comes to price. Both NAS specific models include a three-year warranty as well.
Both drives are standard 3.5" form factor units.
Looking at the drives, we don't see any physical feature that stands out.