What's the difference between neuroglial cells, Schwann cells, and myelin sheath?

Question

What's the difference between neuroglial cells, Schwann cells, and myelin sheath?

Answer 1

Myelin sheaths are electrically insulating coverings for axons in both the central and peripheral nervous systems.  These sheaths allow faster transmission of action potentials at lower energy expenditure.

In the periphery the myelin sheath is created by Schwann cells wrapping themselves around the axons.

In the central nervous system the myelin is created by oligodendrocytes, one of the types of glial cells in the brain.