Side-by-Side Comparison
USB
USB-A vs. USB4
Comparing 2 standards across 8 specifications. 8 key differences identified.
Comparing:
USB-A
USB4
USB-A (Standard-A) is the flat rectangular connector on host ports -- computers, chargers, hubs. It used 4 pins for USB 1.x/2.0 speeds; a 9-pin variant, adding 5 SuperSpeed contacts, extended it to USB 3.0+ in 2008 without changing the external shape or requiring a new socket design.
USB4, released August 2019, is built on Intel's Thunderbolt 3 protocol, donated to USB-IF as the new foundation -- up to 40 Gbit/s, a mandatory USB-C connector, and tunneling that lets a single port carry USB, DisplayPort, and PCIe traffic at once. Thunderbolt 3 compatibility is required; Thunderbolt 4 compatibility is optional for device makers.
Specification Comparison Table
8 Parameters| Parameter / Spec | ||
|---|---|---|
|
Pin Count
|
4 (USB 1.x/2.0) or 9 (USB 3.0+, adds 5 SuperSpeed contacts) | — |
|
Standard Base Dimensions
|
~12 x 4.5 mm | — |
|
Reversible
|
No | — |
|
Typical Role
|
Host / downstream-facing port | — |
|
Released
|
— | August 2019 |
|
Max Bandwidth / Data Rate
|
— | Up to 40 (Gen 3x2) or 20 (Gen 3x1) Gbit/s |
|
Connector Required
|
— | USB-C only |
|
Protocol Foundation
|
— | Intel Thunderbolt 3 (donated to USB-IF) |
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