Both circuit breakers and fuses protect wiring by preventing overloads of current from continuing to pass through electrical circuits. However, breakers and fuses differ in how they work.
A circuit breaker has a bimetallic strip that is sensitive to heat. For small current overloads, the heat generated causes one of the metals to expand at a different rate than the second metal, and bends the strip downward to release a lever.
For large current surges, a small electromagnet with wire loops pulls the strip down to release the lever.
A fuse has a metal filament that melts when exposed to extra heat generated by currents higher than what the fuse is rated for. The melted filament breaks the circuit path.
The service panel contains the devices used for circuit protection. The panel goes by many different names such as breaker box and fuse box.
Breaker boxes are the most common modern service panel and contain circuit breakers.
Fuse boxes are older service panels and contain fuses. Because of the fire hazard posed by fuse panels, many locales no longer allow them in new construction.
However, fuses still play a critical role in protecting electrical appliances and vehicles.