An Ethernet Connection is a type of Network connection that is used for setting up internet on your Local Area Network (LAN). Therefore, Ethernet and LAN are the same and the connector that is used to create the network connections is most typically an RJ4 Connector/
The Difference between the two plugs is primarily where they are used. An RJ45 Jack is used for network connections with computers or other networks. An RJ11 is a cable connector used in phone jacks with phone cables. An RJ45 is an Ethernet cable.
A Category Five or “cat 5” running between two points should not exceed 328 feet (100 Meters). This is the cheapest option however the cat 5 Cables are susceptible to interference and can slow down your network connection.