USB4 vs. Thunderbolt 4: Who Sets the Rules, What’s Guaranteed, and How Cables Get Certified

If you’ve ever wondered why two laptops with the same USB-C port behave differently with the same dock, the answer comes down to who sets the rules and how strictly those rules are enforced. USB4 and Thunderbolt 4 share a connector and many technologies, but they’re governed, tested, and labeled by different organizations with distinct goals. Understanding those players and what certification really looks like, especially for Thunderbolt cables, will save you time, money, and a few sighs.

Who’s in charge of what?

• The USB-IF (USB Implementers Forum) develops the USB4, USB Type-C, and USB Power Delivery specifications and oversees the USB-IF Compliance Program. Passing compliance grants you the right to use Certified USB logos and appear on the USB-IF Integrators List. In short, the USB-IF defines the open standard and manages the logo program for “USB4 20Gbps” and “USB4 40Gbps” ports, as well as power logos.
• Intel owns Thunderbolt (the tech and the trademark) and runs a separate, mandatory Thunderbolt certification for hosts, docks, devices, and cables. Thunderbolt 4 is built on top of USB4, but it tightens what’s optional into must-haves and adds additional requirements (such as security and wake-from-sleep behavior). Fun fact: Thunderbolt was developed in collaboration with Apple.
• VESA (DisplayPort) and PCI-SIG (PCI Express) don’t certify Thunderbolt/USB gear directly for consumers, but their specs are the signals that USB4/Thunderbolt can tunnel. The USB-IF even publishes a “USB4 ↔ Thunderbolt 3 compatibility” test, ensuring that USB4 products play nicely with existing Thunderbolt 3 gear.

USB4 in plain English (and why experiences vary)

USB4 is the USB-IF’s latest high-speed spec that unifies USB-C for data, display, and power. A USB4 product that passes USB-IF compliance can use Certified USB logos; the program tests electrical/protocol behavior, interoperability, and logo usage before listing the product. Importantly, many capabilities, such as PCIe tunneling or the number of displays that can be driven, are allowed in USB4 but not always required, so implementations vary by laptop and dock.

USB-IF logos (“USB4 20Gbps,” “USB4 40Gbps,” and power logos) are reserved for products that have passed USB-IF compliance; misuse is strictly prohibited. That’s your signal a USB product has been through the USB-IF test gauntlet.

Thunderbolt 4: A stricter badge on top of USB4

Thunderbolt 4 takes USB4’s building blocks and adds minimum guarantees. Intel’s published materials highlight three user-visible ones:

• Performance & displays: 40Gbps link rate plus host support for two 4K displays or one 8K display as a baseline.
• PCIe bandwidth: 32Gbps (PCIe x4) available to peripherals important for fast storage and pro devices.
• Ecosystem behaviors: Cables certified up to 2 meters at 40Gbps (“one cable that just works”), required DMA protection (e.g., Intel VT-d), and wake-from-sleep via a docked keyboard/mouse.

A common misconception: Thunderbolt 4 does not mandate “100W host charging” across the board. Intel’s guidance is that thin-and-light laptops that require <100W must support charging on at least one port; docks commonly provide 60–100W, but that’s a product choice, not a universal TB4 rule. 

Thunderbolt logos (the lightning bolt) indicate Intel certification. Intel materials explicitly state: certification is mandatory for computers, accessories, and cables using the mark.

How certification actually happens (overview)

USB-IF compliance (USB4 / USB-C / USB PD)

1. Pre-cert: Vendors prepare at an Authorized Test Lab (ATL) using USB-IF tools and matrices.
2. Testing: Products are evaluated for USB2/USB3, USB PD, Type-C functionality, and USB4 electrical/protocol behavior; results are submitted to USB-IF.
3. Approval: Passing products receive a TID, can license Certified USB logos, and are listed publicly.

For USB-C cables, there’s also explicit testing of the E-Marker (the chip inside the connector that reports capabilities like current, speed, and whether the cable is active/passive). USB-IF publishes the E-Marker test methodology for labs.

Thunderbolt 4 cable certification (Intel-run)

1. Engage an Intel-authorized lab (e.g., GRL, UL, Allion). They run Intel’s Thunderbolt test suites and pre-compliance guidance.
2. Signal integrity at 40Gbps over the target length (up to 2 m for universal TB4 passive cables) with strict eye-diagram, insertion loss, and crosstalk limits. Active cables have integrated signal-conditioning silicon and are tested accordingly.
3. Protocol & interoperability across TB4/TB3/USB4 hosts and devices, including display tunneling and PCIe behavior. (Intel’s program makes these minimums part of certification.)
4. USB-C / PD cross-checks, including validation of the E-Marker contents and power capabilities because Thunderbolt cables still negotiate power using USB PD and must accurately advertise rating (e.g., 100W or newer 240W EPR on some models).
5. Branding review & final approval: Passing cables are granted the right to use the Thunderbolt logo and be marketed as Intel-certified.
   
   

Why it helps you: That process is why a TB4 cable can be “one cable to rule them all” plug it into a Thunderbolt, USB4, or even many USB-C ports and it will behave predictably, including carrying display signals and high-speed data at the rated length.

So… USB4 or Thunderbolt 4 for my setup?

• Pick USB4 when you’re cost-conscious and your needs are modest (single display, mainstream storage, general peripherals). Look for Certified USB logos to avoid guesswork.
• Pick Thunderbolt 4 when you want predictability and headroom: dual-display guarantees, robust PCIe for fast storage or pro gear, and long certified 2 m cables that maintain 40Gbps.

Either way, a certified cable matters. Thunderbolt 4 cables are validated end-to-end under Intel’s program; USB4-certified cables go through the USB-IF’s E-Marker and electrical testing. That’s the difference between “it should work” and “it will work.”

Quick answers to common questions

Does Thunderbolt 4 “force” 100W laptop charging?
No. Intel’s guidance focuses on thin-and-light laptops that need <100W those should support charging on at least one port. Actual wattage on docks and cables depends on the product’s USB PD support (some modern TB4/USB4 cables even advertise 240W EPR). 

Are longer Thunderbolt 4 cables okay?
Yes up to 2m is explicitly called out for universal TB4 cables at full 40Gbps. Beyond that, you’ll typically use active copper or optical solutions that undergo separate certification. 

The Plugable take

At a high level, Thunderbolt 4 is best thought of as “USB4 with guarantees.” It bundles what USB4 makes optional into a consistent, certified experience and couples it with a rigorous cable/device program. That’s why many power users opt for a TB4 dock and a TB4-certified cable even when they’re plugging into a mix of USB-C and USB4 systems.