Does Thunderbolt speed provide a benefit over USB 3.0 for an external hard disk?

Solution 1:

In this ssd benchmark the fastest SSD (2016) has a write performance of 512MB/s (read performance is a little bit higher, but not significantly)

Wikipedia shows 5GB/s as maximum throughput of an USB 3.0 port.

As you can see, this is a multiple of the maximum of what a current hard disk can support.

To answer your question: There is no external hard disk (at the moment) that would use the higher speed of thunderbolt.

An article from 2 years ago did explicit tests and found out: no difference in speed for thunderbolt vs. USB 3 regarding hard discs.

Solution 2:

Yes, PCIe based SSD like the Samsung 950 Pro or the Intel SSD 750 can have read speeds larger 2 GB/s (Gigabyte, not Gigabit).

Here using the SSD in in enclosure connected via Thunderbold 3

gives you a dramatic perf improvement over using a SATA SSD in an USB 3.0 enclosure.