Dedicated Server command line ?listen or -server

Reading the documentation, the parameters for launching the compiled Dedicated Server is not really clear for me.

What is the behaviour of a dedicated server with /Games/Maps/AnyMap?listen
and with -server

When I check the log, the output is very different.

I just need clients to be able to connect to a dedicated server and seeing each others.

Do I have to start the server with ?listen or with -server

Any help will be great.
D.