Here's a breakdown:

* Atoms: The basic building blocks of matter. They consist of a central nucleus (containing protons and neutrons) surrounded by a cloud of electrons.

* Molecules: Two or more atoms held together by chemical bonds. These bonds form when atoms share or transfer electrons.

For example:

* Water (H₂O): Two hydrogen atoms and one oxygen atom bond together to form a water molecule.

* Carbon dioxide (CO₂): One carbon atom and two oxygen atoms bond together to form a carbon dioxide molecule.

* Sugar (C₁₂H₂₂O₁₁): Twelve carbon atoms, twenty-two hydrogen atoms, and eleven oxygen atoms bond together to form a sugar molecule.

It's important to note that not all combinations of atoms form molecules. For example, noble gases like helium and neon exist as single atoms and do not readily form bonds with other atoms.