An atom is the smallest component of an element, while a molecule is made up of two or more atoms. While atoms comprise protons, neutrons, and electrons, molecules comprise two or more atoms that are combined chemically.
Atoms cannot be divided into smaller atoms, while molecules can be divided into component atoms.
An atom can exist independently and may be unstable if the outer shell is not completely filled. Molecules exist as a stable combination of two or more atoms. For example, an atom of Sulphur can exist as S, while a molecule of Sulphur exists as S8.