The difference between lan and wan has been cleared in the following post.
LAN (Local Area Network) is a computer network covering a small geographic area, like a home and office. LANs have a high data transfer rate .One LAN can be connected to other LANs over any distance via telephone lines.Because it covers a relatively small geographical area, LAN is easier to maintain at relatively low costs.
WAN (Wide Area Network) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries. Internet is the best example of a WAN. WANs tend to use technology like ATM and Frame Relay for connectivity over the longer distances. Computers connected to a wide-area network are often connected through public networks, such as the telephone system. They can also be connected through leased lines.WANs have a lower data transfer rate as compared to LANs.