quick guide to Thunderbolt 3 and USB-C cables

Even the most tech-savvy are hard-pressed to describe the features of Thunderbolt 3 and USB-C interfaces and make a clear decision as to why one is better than the other. This quick guide will help you better understand the differences you need to know!

For the first two generations of Thunderbolt (2011) and Thunderbolt 2 (2013), Intel relied on the Mini DisplayPort connection. These iterations were primarily limited to Apple devices and not compatible with USB devices. That all changed in 2015 with the introduction of Thunderbolt 3. This new generation used the more versatile USB-C connection with the goal of interoperability and consistent performance across different computer and peripheral manufacturers. 

What’s driving a bit of the confusion is the ports look identical, and the only way to differentiate them visually is to look for the Thunderbolt logo imprint.

thunderbolt 3 and usb-c cables compared

The simplest way to describe these interface differences is that USB-C (aka USB Type-C) refers to the connector (port) and cable specification, whereas Thunderbolt 3 refers to the capabilitiesthat are available over USB-C. Perhaps that’s why Thunderbolt 3 is billed as “the USB-C that does it all” because, with it, you can connect to Thunderbolt devices, displays, and billions of USB 3.1/3.0/2.0 devices.
While the port they share looks the same, here are the key differences:

SPEED Up to 40Gb/sUp to 10Gb/s
DISPLAY Two 4K displays or one 5K displayOne 4K display
EXTERNAL GRAPHICS Uses PCIe bus which enables use of eGPU

Cannot use eGPU


  • Thunderbolt 3 (and Thunderbolt 2/Thunderbolt devices using adapter)
  • USB-C devices
  • Legacy USB 3.x/2.x devices using adapter with speed limited to device capabilities
  • USB-C devices
  • Legacy USB 3.x/2.x devices using adapter with speed limited to device capabilities
  • Note: NOT compatible with Thunderbolt devices

EXPANSION Daisy-chain up to 6 devicesCan only connect one device*

The Most Important Take-Away…

All Thunderbolt 3 ports are also USB-C ports, but not all USB-C ports are Thunderbolt 3 ports.

Should You Use Thunderbolt 3 or USB-C? For everyday personal computing uses, USB-C devices offer an attractive balance of price and performance. If you own a Thunderbolt 3-equipped computer AND require pro-grade external storage transfer rates, multiple HD monitors, docks with numerous functionalities like Ethernet and card reader, or the ability to use an eGPU, then Thunderbolt 3 devices are the way to go.

Author: OWC Mark C

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