circuit breaker vs safety fuse

circuit breaker and safety fuse both are nouns.

Word	Noun	Adjective	Verb	Adverb
circuit breaker	Yes	No	No	No
safety fuse	Yes	No	No	No

As nouns, safety fuse is a hypernym of circuit breaker; that is, safety fuse is a word with a broader meaning than circuit breaker:

circuit breaker: a device that trips like a switch and opens the circuit when overloaded
safety fuse: an electrical device that can interrupt the flow of electrical current when it is overloaded

Other hypernyms of circuit breaker include electrical fuse, fuse.

circuit breaker (noun)	safety fuse (noun)
a device that trips like a switch and opens the circuit when overloaded	a slow-burning fuse consisting of a tube or cord filled or saturated with combustible matter; used to ignite detonators from a distance
	an electrical device that can interrupt the flow of electrical current when it is overloaded