They are different shapes, each shape has both a plug and a corresponding socket. USB A is the traditional rectangular plug/socket, while USB B is the bulky somewhat square shape usually found in printers. There are also mini and micro versions of both A and B, each having both a plug and a socket.

The traditional USB connection has a host with a USB A socket, which provides power; a cable with a USB A plug in one end and a USB B plug in the other end; and a device with a USB B socket. All traditional USB cables are A to B cables, with a USB A plug and a USB B plug; an A to A cable would allow connecting two hosts together, and both would try to provide power at the same time, which might damage the hardware.

USB-C is completely different; all cables have two USB-C plugs, while both hosts and devices have USB-C sockets. Which side provides power is negotiated through a dedicated configuration channel.

USB A and B are both connector types, just like USB C is a connector type. The letters have nothing to do with male vs. female.

USB A is a rectangle, and USB B is closer to a square. I've also never seen anything aside from female USB ports and male/male USB cables (aside from extension cables).

For USB cables there is a host side (type A plug) and a device side (type B plug). These come in standard, mini and micro. You probably havent seen anything but a standard type A (this bit you recognise as the side that plugs into a computer), but are probably familiar with each of the type-b connectors.

Type C is bi-directional, so can replace either or both plugs.

The USB standard has a lot of connectors

https://itsolutionindia.files.wordpress.com/2014/08/usb-tuto...