Q: What is the difference between a GFCI and Circuit Breaker?

A: A GFCI is designed to prioritize operator safety by detecting and interrupting current leaks. This interruption can be triggered by an imbalance between the hot and neutral lines, even as small as 4 to 5 milliamps. It can also be triggered if power flows through something other than the intended circuit, like a human.
A circuit breaker protects equipment by preventing circuit overheating. For example, a 5A circuit breaker limits the current flow to 5A or less.