Asteroid 
Small, irregular shaped rocky body orbiting the Sun
Asteroid Belt 
Group of asteroids between the orbit of Mars and Jupiter
Earth Crossing Asteroids 
Asteroids whose orbit pass within the orbit of the Earth.
Same as Apollo Group
Comets 
Bright objects with long, wispy tail that always points away from the sun
Meteorite 
Fragments of extraterrestrial material that strike the surface of the Earth
Meteoroid 
Fragment before hits the ground