I will be able to explain comets, asteroids and meteors using the differences each possess.
http://www.google.com/url?q=http%3A%2F%2Fscience.nationalgeographic.com%2Fscience%2Fspace%2Fsolar-system%2Fasteroids-comets-article%2F&sa=D&sntz=1&usg=AFQjCNF2vx2IzOyvwXsKK02INNaJgYiTLQ
Source: National Geographic
Source: tutor vista