There's also the USB Type-B Mini, a five-pin version introduced in the year 2000. It is commonly used in smaller devices where a standard USB-B port would be too bulky.

The USB Mini-B is a five-pin connector that came out at the same time as the USB 2.0 standard in 2000. The new standard was an improvement over earlier versions and supported data transfer speeds ...

The difference in shape also means you cannot use USB-B 3.0 connectors with older USB-B 2.0 or USB-B 1.1 ports. However, USB-B 3.0 ports are designed to accept older USB-B connectors.