The primary and most noticeable difference between USB 4.0 and USB-C is that USB-C is a form of USB cable. This applies to the physical design of the connections and ports, whereas USB 4.0 is concerned with the USB cable's functionality and speed. Simply told, USB 4.0 is the most recent version of USB that is incorporated within a USB-C cable. Another distinction is that while the actual USB-C connector is not backward compatible, the underlying USB specification is. Older USB devices cannot be plugged into a contemporary, small USB-C connector. A USB-C connection cannot be linked to an earlier, more oversized USB port. In contrast, USB 4.0 has fewer restrictions and fully allows backward compatibility with earlier generations.