A LAN and a USB Internet connection are two entirely different things. A LAN is a network structure. A USB Internet connection is connecting a computer to networking equipment with a USB cord instead of an Ethernet cord or a wireless adapter.

Local Area Networks

LANs are groups of computers in the same general area, such as a house or office, that are linked together locally by the same networking equipment. This makes it easier for computers to connect directly to one another, and lets all the computers on the LAN share Internet access and networked storage devices.

Networking Cables

Computers generally connect to a LAN's networking equipment through either wireless network adapters or Ethernet cables. Computers can also connect to the network through USB cords if the networking equipment has USB connection ports. Ethernet cords are used more often in networking than USB cords. They are easier to find in much longer lengths than USB cords and are capable of higher bandwidths than USB cords. As of 2013, USB cords could transfer up to 4.8 gigabytes per second while Ethernet cords could transfer up to ten gigabytes per second.