Alan.
USB card' and 'USB adaptor are one and the same.
To my knowledge, All USB devices manufactured today are external! The connector (where you plug the cable in) is connected to the motherboard, either as build-in or through the use of a PCI card. The connector part is outside the computer just like the connector for your video card.
The main reason for suggesting a USB connector is that Hoster is bound to a
unique Ethernet MACID No. So when you take the USB connector to another computer, you are in fact, transferring the MACID ID Number. Therefore, Hoster thinks it's running on the same computer.
I hope this helps you leave the sidelines and join the game.
Regards,
Jon