Is USB-C the same as Thunderbolt? The plug is shared, the abilities are not

One plug, several technologies

Intel, which is the steward of the Thunderbolt specification, describes Thunderbolt as working through a USB-C connector by using USB 2, USB 3, USB4, DisplayPort and PCIe protocols. Its list of uses is monitors, docks, storage, external graphics and other accessories.

USB itself spans a wide range over the same connector. USB-IF's logo guidelines describe performance logos for 5, 10, 20, 40 and 80 Gbps, and they note that USB 2.0 Type-C cables carry data at up to 480 Mbps, whatever their power rating. The guide to USB-C cables covers those labels.

How Thunderbolt and USB4 relate

The two are close relatives. USB-IF says USB4 is based on the Thunderbolt protocol specification contributed by Intel, and Intel lists USB4 compliance as a requirement for Thunderbolt 4 and Thunderbolt 5.

What separates them is what gets promised. USB-IF says a USB4 connection scales to the best mutual capability of the devices connected. Intel sets minimums that a product must meet to carry the Thunderbolt name, and says it validates and certifies all products bearing the Thunderbolt logo.

What Thunderbolt requires

The two Thunderbolt 5 figures describe one link used in two ways. Intel says it delivers 80 Gbps in each direction, and that a feature called Bandwidth Boost can rebalance the link when a display needs more, giving 120 Gbps to transmit and 40 Gbps to receive.

How to tell which port you have

Look for the Thunderbolt symbol, a lightning bolt, beside the port. Apple's guide to Mac ports uses it this way, and it also shows why the check matters: on Mac Studio models with M1 Max or M2 Max, the USB-C ports on the front are for devices that connect by USB-C cable, while an external display goes in a port on the back with the Thunderbolt symbol.

If you are unsure, check the specification for your model. Apple's guide lists its ports Mac by Mac.

What about cables?

Apple says a Thunderbolt 3, 4 or 5 cable connects to a Mac's Thunderbolt or USB-C port without an adapter, and so does a USB-C cable such as its 60W charge cable. Fitting is not the same as reaching top speed. USB-IF ties its top rate to 80 Gbps certified cables, and Intel rates universal Thunderbolt cables of up to 2 metres at 40 Gbps for Thunderbolt 4 and 120 Gbps for Thunderbolt 5.

Does any of this matter for charging?

Less than it does for data and displays. Charging a phone comes down to the charger, the cable's power rating and what the phone accepts, which the guide to USB-C Power Delivery explains. Where the Thunderbolt name helps is on a computer, because Intel requires a charging level on at least one port.