motor neurons (efferent neurons; lower motor neurons) are multipolar shaped cells that conduct action potentials out of the central nervous system.
Sensory neurons (afferent neurons) are unipolar, bipolar, or multipolar shaped cells that conduct action potentials toward or into the central nervous system.
Interneurons(internuncial or association neurons) are the billions of cells that form much of the central nervous system and link the sensory and motor neurons