In our solar system, there are millions of heavenly bodies that have this particular instinct of revolving around another bigger heavenly body. For example the planet revolves round the sun, the satellites revolve around their respective planets. Then there are comets and asteroids that also revolve around some heavenly bodies. While we are quite knowledgeable about planets and satellites, we seem to be confused when it comes to asteroids and comets. How to differentiate between them?
An asteroid are usually rocky chunks that revolve round the sun. Asteroids are usually smaller than planets but some can be really huge. The biggest asteroid of our solar system is Vesta 329 miles around whereas the smallest asteroid that has been discovered till date is only 6 feet.
The materials with which these asteroids are made can be of different types from rocky materials, to silica, to metals. Scientists classify asteroids based on the materials they are are built. They are made up of metals, stone, silica, or combinations of any or all of them.
A comet, on the other hand, is made up of ice, in huge chunks. The center of the comet is called nucleus and they remain frozen through out. The comets travel in the outer reach of Solar system. Comets also have orbits but these orbits take them away from the Sun into colder region, unlike asteroids. On rare occasions, orbits of comets bring them closer to the solar system planets. When a comet moves, the dust and gas trails out behind it, which creates an impression of a tail like thing that can stretch for thousands of miles. When they come close to earth the tail gets illuminated by light reflected from the earth and looks like light streaks.
So, here you get the basic difference between an asteroid and a comet.