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While USB-C and Thunderbolt share the same physical rounded rectangle connector they operate in fundamentally different ways.
The Main Differences Aren't Physical
USB 3 at 5Gbps and 10Gbps with Type-C - often simplified to USB-C - is both the hardware connector standard, and the included data types: USB 5Gbps or 10Gbps data rates, as well as optionally DisplayPort Alternate Mode video and USB Power Delivery for powering and charging both host computers, and downstream devices.
Thunderbolt, specifically Thunderbolt 3 and newer and USB4 use the same physical USB Type-C port, and support a backwards compatibility with USB-C devices, however the signaling and data structure is completely different. Both Thunderbolt and USB4 operate at between four to sixteen times the speed of USB 3. While USB offers optional display and charging, these are mandatory for Thunderbolt hosts. The way display data is transmitted is also different.
DisplayPort Alternate Mode for USB 3 occupies two or four of the physical data lanes in the USB Type-C connector and cable. Tunneled DisplayPort video in Thunderbolt (and USB4) packetizes the DisplayPort video data and transmits it within Thunderbolt/USB4 data packets. Tunneled DisplayPort allows for more native DisplayPort streams enabling multiple external displays at higher resolutions and refresh rates.
Power Delivery is the USB Type-C (as in the port) charging and power standard - this allows a power source and device to negotiate a voltage and maximum amperage both devices can support. For example a phone might negotiate a 9V 3A charge rate which is close to optimal for a phone size battery, while a notebook computer is more likely to negotiate 20V 5A both for improved battery charging and to power the system under moderate to heavy workloads.
Why USB-C and Thunderbolt Capabilities Differ
USB Type-C is a connector standard where features such as video output (DisplayPort Alt Mode) and USB Power Delivery (PD) are optional and depend on the host device manufacturer. In contrast, Thunderbolt sets mandatory performance and hardware requirements across data, video, and power protocols.
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USB 3.0 / 3.1 Gen 1: Up to 5Gbps data transfer speed.
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USB 3.2 Gen 2: Up to 10Gbps data transfer speed.
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USB 3.2 Gen 2x2: Up to 20Gbps data transfer speed. This is very rarely implemented and most computers do not support it.
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Thunderbolt 3: Up to 40Gbps data transfer speed, supports dual DisplayPort 1.2 enabling two 4K or a single 5K displays, USB, DisplayPort, PCIe over a single cable, and up to 100W Power Delivery.
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USB4: Up to 40Gbps data transfer speed, supports DisplayPort 1.4 either one or two external displays, PCIe, and optional Thunderbolt 3 compatibility, USB 3.2 Gen 2 10Gbps, and Power Delivery.
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Thunderbolt 4: Up to 40Gbps data transfer speed, supports dual 4K or single 8K displays, USB4 compatibility, USB 3.2 Gen 2 10Gbps, and Power Delivery.
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Thunderbolt 5: Up to 80Gbps bi-directional bandwidth (DisplayPort up to 120Gbps using Bandwidth Boost), supports dual 6K or single high-refresh-rate 8K displays, PCIe, and backward compatibility with Thunderbolt 4 and USB4, USB 3.2 Gen 2 10Gbps.
Effectively each tier from this list supports all of the features of the tier above as well as some new features. Thunderbolt 4 is Intel's implementation of USB4 with all optional features enabled.
How to Identify Ports and Ensure Compatibility
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Port Identification: Thunderbolt ports are usually marked with a lightning bolt symbol with a downward pointing triangle at the bottom point, this should be next to the port, while USB-C ports may be unmarked or feature symbols indicating power delivery (a simple lightning bolt is common) or DisplayPort capabilities ("DP" logo is often used). Always refer to device technical specifications for confirmation.
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Connecting Thunderbolt Devices to USB-C Ports: Thunderbolt 3, 4, or 5 devices connected to standard USB-C ports typically operate at reduced capabilities, such as lower speeds or fewer display outputs.
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Connecting USB-C Devices to Thunderbolt Ports: USB-C devices connected to Thunderbolt ports function normally, but cannot take advantage of full Thunderbolt features.
Applicable To
- Plugable docking stations, hubs, and video adapters
- USB-C standards (USB 3.0, 3.1 Gen 1, 3.2 Gen 2, 3.2 Gen 2x2, USB4)
- Thunderbolt standards (Thunderbolt 3, Thunderbolt 4, Thunderbolt 5)
If you have any questions please feel free to contact us at support@plugable.com and we'll be happy to help!