A dipole refers to a separation of positive and negative charges within a molecule, resulting in a positive end and a negative end. This occurs when there is an uneven distribution of electrons between atoms in a bond. In contrast, a polar molecule is a molecule that possesses a dipole moment, meaning it has a distinct positive and negative end due to its asymmetrical shape and the differences in electronegativity between the bonded atoms.
To further clarify, not all dipoles are classified as polar molecules, but all polar molecules exhibit dipole characteristics. For example, water (H2O) is a polar molecule because of the bent shape and the difference in electronegativity between hydrogen and oxygen, creating a dipole. On the other hand, a linear molecule like carbon dioxide (CO2) has dipoles (due to the difference in electronegativity between carbon and oxygen) but cancels them out due to its symmetrical shape, resulting in a non-polar molecule.