There's only one major feature that sets the 5000 Plus apart from the 5000 series, it's what Rain Bird calls Stream Control Technology. Simply put, you can turn off the sprinkler while it's in operation. Makes it easy to change nozzles, adjust the arc, ectera. Hunter's I-20 has the same exact feature, and I love it. Wrong nozzle? No problem. Instead of having to run back to the controller, all you do is turn off the individual head while everything else is running. Arc not set quite right? Turn off the flow and set it.
FC vs PC. Simply put, PC is the part circle adjustable version and is capable of covering a full circle. The full circle model is just that, a full circle model. The arc is not adjustable.