In a single line, LAN (Local Area Network) card address is called MAC address. LAN card address is also called Physical address. Generally when your PC is connected with net an IP (Internet Protocol) address is fixed for your PC. Everytime when your PC connects with net, a different IP address will be fixed for your PC by its vacancy. It is done automatically. No one controls it. But MAC address is always fixed. Every LAN Card has unique MAC Address.