What is the actual difference between Java RMI and RPC?
I have read in some places that RMI uses Objects?
RPC is C based, and as such it has structured programming semantics, on the other side, RMI is a Java based technology and it's object oriented.
With RPC you can just call remote functions exported into a server, in RMI you can have references to remote objects and invoke their methods, and also pass and return more remote object references that can be distributed among many JVM instances, so it's much more powerful.
RMI stands out when the need to develop something more complex than a pure client-server architecture arises. It's very easy to spread out objects over a network enabling all the clients to communicate without having to stablish individual connections explicitly.