USB 3 vs Thunderbolt: which cable should you use?

The external-port decision that shapes how fast you can back up.

Thunderbolt 4 (and its twin, USB 4) runs at 40 Gbps — 8× the speed of USB 3.0's 5 Gbps and 4× that of USB 3.2 Gen 2's 10 Gbps. For bulk data transfer and external SSDs that advantage is immediate and obvious: 1 TB copies in about 3.5 minutes on Thunderbolt vs 27 minutes on USB 3.0. Thunderbolt also does things USB 3 can't do natively: daisy-chain up to 6 devices, pass a 4K 60 Hz display signal alongside data, and deliver up to 100 W of power.

See 1 TB over Thunderbolt 4

The 3-minute external-SSD scenario on a TB4 cable.

See 1 TB over USB 3.0

How long a 1 TB backup takes over legacy USB 3.0.

See 100 GB over USB 3.0

The common large-folder copy over 5 Gbps USB.

Option A

USB 3 (3.0 / 3.2 Gen 1)

Wins 2 of 11 compared specs

Option B

Thunderbolt 4 / USB 4

Wins 6 of 11 compared specs

Side-by-side specs

Spec	USB 3 (3.0 / 3.2 Gen 1)	Thunderbolt 4 / USB 4
Max data rate	5-20 Gbps (versions)	40 Gbps (TB4/USB4) / 80 Gbps (TB5) (better on this spec)
1 TB transfer time (peak)	26m 40s (USB 3.0)	3m 20s (TB4) (better on this spec)
Connector	USB-A or USB-C	USB-C only
Display support	Alt Mode (limited)	Full DisplayPort 1.4/2.1 tunnel (better on this spec)
Max displays	1 (sometimes)	2 at 4K 60 Hz (TB4) (better on this spec)
Power delivery	Up to 100 W (USB-C PD)	Up to 100 W (minimum)
Daisy-chain	No	Up to 6 devices (better on this spec)
PCIe tunnelling (eGPU)	No	PCIe 4.0 x4 (better on this spec)
Typical cable price (1 m)	$5-15 (better on this spec)	$30-70
Backwards compatible	Both ways with older USB	Accepts USB 3 devices
Found on budget laptops	Always (better on this spec)	Rarely

How they differ

USB 3.2 Gen 2 (10 Gbps) and USB 3.2 Gen 2×2 (20 Gbps) narrow the raw-speed gap, but Thunderbolt keeps its feature advantage in display and PCIe tunnelling. On a MacBook, Thunderbolt lets you daisy-chain a 4K monitor, an external GPU enclosure, and a fast SSD to the same port; no USB 3 variant supports the full PCIe tunnel and DisplayPort Alt Mode combination Thunderbolt uses. Physical connectors are identical — both use USB-C — so compatibility is a matter of what silicon sits behind the port. A Thunderbolt port always accepts USB 3 devices (and cables) at reduced speed; a USB 3 port doesn't accept Thunderbolt devices at all.

Verdict

For a single external SSD or hub, USB 3.2 Gen 2 (10 Gbps) is enough and widely supported. For anything involving large-transfer workflows (video editing, backups, eGPU enclosures, chained displays), Thunderbolt 4 is the only answer. If your laptop has both, use Thunderbolt unless you explicitly need a USB 3-only device.

See 1 TB over Thunderbolt 4

Which should you pick?

Choose USB 3 (3.0 / 3.2 Gen 1)

Pick USB 3 for general peripherals, single external drives, keyboards, webcams, and any device where 5-10 Gbps is comfortably more than the bottleneck. It's cheaper and universal.

See a 100 GB transfer over USB 3

Choose Thunderbolt 4 / USB 4

Pick Thunderbolt 4 / USB 4 for external SSDs over 1 TB used regularly, for daisy-chained displays, eGPUs, docking stations driving multiple 4K monitors, or high-bandwidth audio/video capture.

See 1 TB over Thunderbolt 4