I need to design a UI that includes widgets to control a server computer, and a client computer.
This means I'll be doing similar pairs of icons for mail (mail program vs mail server), web (browser vs apache settings), and so on.
Is there a conventional way to visually distinguish between client and server?
I notice Apple uses a "tray" to indicate a server service, but I'm not sure this would be clear enough for the average user of my program.
Eg: Server:
vs Client: 



