Atoms are the thing that make up molecules and compounds. Molecules contain two or more atoms and are held together by covalent bonds, whereas compounds are held together by ionic bonds.
The atoms within a compound also must be different from eachother, whereas a molecule can consist of only one element.
Molecule is the general term used to describe any atoms that are connected by chemical bonds. Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements. All compounds are molecules, but not all molecules are compounds.
