I don't know about the mixtures, but I can tell the differences between the compound and the molecule. A Compound is a substance made up of two or more different elements joined together and the Molecule is a substance made up of two or more atoms joined together.
None. A mixture requires at least two substances. A molecule is the particle of only one substance. Elements and compounds can both exist as molecules. Neither compounds nor mixtures are necessarily molecular. There is no definite relationship between these terms.