Advantages of WiFi USB Adapters
WiFi USB adapters connect to a PC's motherboard through the USB port. They are very easy to use as all you need to do is plug it into the WiFi client’s (laptop, camera, smartphone, and printer among others) USB port, and either install drivers or wait for the system to install the drivers. As soon as the appropriate drivers have been installed, you can connect to a wireless network using your credentials.
Wireless PCI Cards
A wireless PCI card is a device that plugs into the WiFi Client’s motherboard through the PCI slot. They are typically not very portable due to having several antennas that stick out from the back to give a stronger signal.