Today’s Question: Please let me know what the term “Thunderbolt” implies in relation to external hard drives.
Tim’s Quick Answer: Thunderbolt is a type of hardware interface that is used on some external hard drives and other devices. In concept a Thunderbolt data connection implies fast speed, but in reality the hard drive itself prevents the maximum theoretical speed to be achieved. In other words, you will typically get about the same transfer speed with Thunderbolt or USB C.
More Detail: Thunderbolt is a hardware interface originally created by Intel in conjunction with Apple, used to connect various hardware devices together, such as to provide a data connection between a computer and an external hard drive. Thunderbolt had been common on Apple computers, but has more recently been somewhat replaced by the latest version of the USB standard.
The latest hardware often makes use of a USB C connector, which is used for both USB and Thunderbolt connections. The latest version of USB provides a theoretical maximum speed of 1.25GB per second, while Thunderbolt 3 offers 5GB per second). However, top drives typically provide maximum throughput speeds of about 500MB per second. In other words, similar performance could be expected with a USB C or Thunderbolt connection because the interface provides higher speeds than the actual storage device can keep up with.
While the latest Thunderbolt interface makes use of a USB C connection, there are differences beyond the maximum potential speeds noted above. For this reason, not all devices will be compatible across all connections.
Also note that many of the external hard drives currently available that offer Thunderbolt are making use of an older version of Thunderbolt. Those drives offer performance closer to what USB is capable of today. But again, in either case the bottleneck for data transfer is generally the hard drive, not the data connection used to connect the drive to the computer.
Ultimately I recommend selecting hard drives with a data connection that suits the ports available on your computer. And I recommend selecting a computer based on your more general needs. I wouldn’t consider Thunderbolt to be a critical factor in selecting a computer or peripheral, considering the excellent performance that is also available with USB connections.