Correct me if I'm wrong here but I think you're talking about two different things. Content Staging will keep track of your content changes in the database which you can then sync to another server (Dev -> Staging). A web farm would have 2 servers (or more) in your Dev environment which would sync physical files back and forth between the servers in that farm. There would be no way to sync those physical files from Dev to Staging without some sort of manual setup/process. And Kentico doesn't do that out of the box.

To go further in detail, in your Dev environment you have Server1 and Server2 and you access it via a load balancer by calling dev.mydomain.com the load balancer decides which server you access. So you want all your files in sync on both those servers. Those two servers also will connect to the same database, we'll call it Dev.

Now in your Staging environment you have Server3 and Server4 and you access it via a load balancer by calling stating.mydomain.com. Both those servers connect to the same database, we'll call it Staging.

When you perform an action within Content Stating, you are pushing change in the Dev database to the Staging database (or visa versa). When your web farm servers sync, you are syncing the physical files (aspx, ascx, .cs, etc.) from Server1 to Server2 (and visa versa) and from Server3 to Server4 (and visa versa).