Even I have trouble understanding the real difference between ground and neutral, because neutral connects to ground in the breaker panel. I'm not even sure if neutral goes through the breaker?
> Even I have trouble understanding the real difference between ground and neutral,
Neutral is the normal return path for current. Under normal operation power is delivered to a device via the "hot" conductor, and travels back from the device to the source over the neutral conductor.
The ground conductor is present for safety purposes. Under normal operation no current should flow over the ground conductor at all. The only time the ground should have a current flow is during a safety event (i.e. a short from hot to the case of a device with a metal case).
> I'm not even sure if neutral goes through the breaker?
It does not, the breaker is present in the "hot" conductor path, and tripping the breaker disconnects just the hot conductor from the power source.
1. It's to provide protection in case of neutral failure. If you have an appliance with the case grounded via neutral and the neutral wiring fails, you now have the case connected to live (through any appliance that is switched on). With separate ground, nothing happens as you are only allowed to connect ground to neutral at a point where failure of the upstream wiring is practically impossible (i.e., wires so thick that they practically won't break).
2. It's to provide a path for ground fault currents that does not pass through the RCD, if you have an RCD. While neutral doesn't go through the circuit breaker, it does go through the RCD, so as to measure the difference in current between live and neutral. If your appliance is grounded vial neutral, any ground fault (connection from live to the case) looks like regular load current to the RCD, if it is grounded via separate ground, the fault current bypasses the RCD and thus causes it to trigger, even for a small current that would not trigger over current protection.
So you have a separate ground that normally sees no voltage at all.
You are correct, the neutral does not go through the breaker. It is usually wired inside the breaker panel though.
Some localities want the neutral and ground wired separately (to separate bus bars), with a single point connecting them, but most don't care and the neutral and ground are attached to the exact same place inside the breaker panel.
Electrically, the neutral and ground are at the same potential, assuming magic wires with zero resistance, but in the real world the wire does have resistance, especially if it was poorly installed, so they are not always at the same potential. There could also be capacitance in the line.
Neutral does not go through the breaker, correct.