What is the difference between a breaker panel and my old fuse panel?

Both devices, either breaker or fuse, are designed to trip (turn off) in the event of an electrical overload, i.e. 20Amps of electrical load on a 15Amp circuit would cause a trip. The only difference is that a breaker is mechanical and may be reset. Whereas, a fuse is one time only and must be replaced. Please Note: Modern breakers are much more efficient and offer greater levels of protection.