RJ is the acronym for Registered Jack and refers to the industry standard character that cable connectors usually start with. RJ45 and RJ11 are the 2 most command connector standards used universally.
The main difference between these two is in where they are actually used. RJ45 jacks are used in networking (Ethernet[p2p type=”slug” value=”what-is-local-area-network”] LAN[/p2p]) , where you connect computers or other network elements to each other. RJ11 is the cable connector that is being used in telephone sets.