Performance of microkernel vs monolithic kernel. As is always the answer (or at least the preface) to performance-related questions: know your problem domain, run comparative benchmarks, and remember what premature optimization is.
A summary of the difference between contactors, motor starters, relays and circuit breakers. Switches, circuit breakers, and contactors are used to control what parts of an electrical system are energized or de-energized. Fuses are used to protect the electrical system when something goes wrong, and can isolate the faulted parts from the normal parts.
The other difference between it and the double-pole circuit breaker is that these two circuit breakers are built into on single space in your electrical panel. A tandem circuit breaker is not always allowed in circuit breaker panels.