Here's a breakdown:

* Comet: A ball of ice and dust that orbits the Sun.

* Broken-up comet: When a comet gets too close to the Sun, its ice melts and the pressure from the Sun's radiation can cause it to break apart.

* Meteoroid: A small piece of rock or dust in space that comes from a comet, asteroid, or other celestial object.

* Meteor: A meteoroid that enters the Earth's atmosphere and burns up, creating a streak of light in the sky.

* Meteorite: A meteoroid that survives its journey through the atmosphere and lands on Earth.

So, the smaller pieces of a broken-up comet are simply smaller pieces of rock and dust floating in space, and they are called meteoroids.