Ethernet is:
Ethernet is One of several methods by which information travels through a network.
Ethernet is the most widely installed local area network (LAN) technology. Ethernet is a link layer protocol in the TCP/IP stack, describing how networked devices can format data for transmission to other network devices on the same network segment, and how to put that data out on the network connection.
Ethernet is a way of connecting computers together in a local area network or LAN. It has been the most widely used method of linking computers together in LANs since the 1990s. The basic idea of its design is that multiple computers have access to it and can send data at any time.
In case you had different LAN interfaces on your system then they could have meant different. ... LAN port means your Local Area Network port which invariably ends up being an Ethernet port. So for all practical purpose LAN port is the same as Ethernet port. The connector used is RJ45.
When using an Ethernet network, the network's router also serves as a bridge to the Internet. The router connects to the modem, which carries the Internet signal, sending and receiving data packet requests and routing them to the proper computers on the network.