First of all, a neck pillow is a pillow with built in support for the neck. A number of names used with neck pillows are: support pillows or contour pillows. Sometimes the definition of orthopedic pillow or pillow that was chiropractic can be used as well.
That said, all Neck Pillows are created to give you support to keep your back in alignment. Some may be shaped like a regular pillow (rectangle), some are square, or maybe curiously shaped in the event that you will. The contour or design Layout or the contour of the pillow shouldn’t make a tremendous difference; it may be more of a personal taste. All neck pillows should have some type of neck support, meaning they’ll hold your spine in a neutral position.It will allow for a curvature in the neck when back sleeping and keep your spine straight when on your side and will allow for a curvature in the neck when back sleeping.