Replicated variables denotes Network States of an Actor while Multicast denotes Network Events on an Actor. The difference is that Events can be unreliable and may or may not be sent to the client at all. The network state could arrive eventually (note that only the most recent state will arrive eventually and intermediate states may be skipped).
Events could be used to elaborate on a game mechanic while it happens, and states could be used for the long term changes to an Actor.
If we use an Elevator as an example.
The Network Events on an elevator could be
- “Call Elevator” button pressed
- Doors Opening
- Doors Closing
- Start Moving Elevator UP/Down
The Network States on the elevator could be
- Is The Doors Open?
- Enum MovementState (Going Up, Going Down, Stopped)
- Height or Level