Buffalo and Freecom do not make actual hard drives, yes they make external drives.
But, Inside you’ll find a variety of drives from different mfg.
WD, Seagate, IBM, Samsung etc…
Whenever getting a ExHDD, you can do a little research and find what mfg is in those specific drive.
afa a Thunderbolt drive, WD does have aMyBook Thunderbolt 