In Solar System astrophysics, isolationism is unfashionable and comparative planetology is all the rage. Astronomers compare Venus with Earth, Mars with Moon and Jupiter with Saturn; so why not compare comets with asteroids? This is the task that I set out to fulfil, but it must be stressed at the outset that, just like the previous examples, comets and asteroids are completely different objects. They have different origins, evolutionary histories, orbits, size ranges, size distributions, compositions, surface features, internal structures, apparent magnitudes, observational histories and end products. Comets and asteroids are often grouped together under the epithet‘minor body'. They are minor because they are smaller than the majority of planetary satellites, and their eccentric orbits often put them on collision courses with the planets. Both comets and asteroids are capable of catering planetary surfaces and, in the present epoch, a minor body > 1 km will hit Earth about every 2 × 106years. This impactor is 20 times more likely to be an asteroid than a comet. Comets decay and asteroids break up. Both these processes produce dust that starts off as a co-orbital meteoroid stream and eventually feeds the general zodiacal dust cloud that surrounds the Sun.