Asteroid: The name “asteroid” means “like a star” in the ancient Greek language. Asteroids may look like small stars in the sky, but they really do move around the Sun, while stars only seem to move because the Earth spins. Like planets, asteroids do not make their own light. Asteroids are the leftover rock and other material from the formation of the Solar System. Most asteroids are made of rock, but some are made of carbon or metal. Depending on what's on the surface, they are classified into various kinds in including Type M (metal), Type S (stone), and Type C (carbon).
Most asteroids in our Solar System are in the asteroid belt between the orbits of Mars and Jupiter. Sometimes their orbits get perturbed or altered and some asteroids end up coming closer to the Sun, and therefore closer to Earth. The asteroids that come close to Earth are called Near Earth Objects (NEO).
Comets: They are much like asteroids, but have more ice, methane, ammonia, and other compounds that develop a fuzzy, cloud‐like shell called a ‘coma’ – as well as a tail – when it gets closer to the Sun.
Comets are thought to originate from two different sources: Long‐period comets (those which take more than 200 years to complete an orbit around the Sun) originate from the Oort Cloud. Short‐period comets (those which take less than 200 years to complete an orbit around the Sun) originate from the Kuiper Belt.
Meteoroid: Space debris smaller than an asteroid are called meteoroids. A meteoroid is a piece of interplanetary matter that is smaller than a kilometer and frequently only millimeters in size. Most meteoroids that enter the Earth's atmosphere are so small that they vaporize completely and never reach the planet's surface.
Meteor: When meteoroids enter Earth's atmosphere, they gain a different name called meteors. Another name commonly used for a meteor is a ‘shooting star’. A meteor is the flash of light that we see in the night sky when a small chunk of interplanetary debris burns up as it passes through our atmosphere. “Meteor” refers to the flash of light caused by the debris, not the debris itself.
Meteorite: If any part of a meteoroid survives the fall through the atmosphere and lands on Earth, it is called a meteorite. Although the vast majority of meteorites are very small, their size can range from about a fraction of a gram (the size of a pebble) to 100 kilograms (220 lbs) or more (the size of a huge, life‐destroying boulder).