Quoted from Dent00:The GFCI Outlet will trip for one of two reasons, overload on the circuit, or a ground fault,
Quoted from MattElder:Electrician chiming in here. This is false. A GFI trips for one reason only... a ground fault. It does not trip due to an overload! It is not an overcurrent device in any capacity.
GFCI and GFI are not exactly the same. https://bates-electric.com/gfi-vs-gfci-outlets/
"The main difference between the GFCI and GFI terminologies is that while a GFI is local, the GFCI is used in the context of both a local receptacle and a circuit breaker which provides ground interference protection for the whole circuit."
And it's a bit misleading to say they trip only on a ground fault because that can lead people to only look for a problem on the ground wire. They will trip on any difference in potential and that could be faulty ground wire or neutral wire, wherever there is a difference between current flowing in and current flowing out. That's one reason you can install one of those outlets on an ungrounded circuit and still be protected.