What is the difference between the bitcoind command line options "addnode" and "connect"?

Question

As seen here: https://en.bitcoin.it/wiki/Running_Bitcoin#Command-line_arguments

-addnode=ip Add a node to connect to and attempt to keep the connection open
-connect=ip Connect only to the specified node(s)

Both of those explanations seem to say the same thing to me.

Can anyone explain them in more detail?

Answer 1

addnode add a node to the list of nodes to connect.
connect only connect to THIS node.

For example, if you are currently connected to the nodes {A, B, C} and then issue…

addnode=D: you'll be connected to {A, B, C, D}
connect=D: you'll be connected to {D}

Answer 2

Some additional guidance is in share/examples/bitcoin.conf to add to Nontenda's answer.

Let's say for instance you use addnode=4.2.2.4, addnode will connect you to and tell you about the nodes connected to 4.2.2.4. In addition it will tell the other nodes connected to it that you exist so they can connect to you.

connect will not do the above when you "connect" to it. It will only connect you to 4.2.2.4 and no one else. So if you're behind a firewall, or have other problems finding nodes, add some using addnode. If you want to stay private, use connect to only connect to "trusted" nodes.

If you run multiple nodes on a LAN, there's no need for all of them to open lots of connections. Instead "connect" them all to one node that is port forwarded and has lots of connections.

Further documentation for addnode is here.