What is the difference between Mees’ lines and Muehrcke’s lines?

Mees’ lines represent single or multiple transverse white lines that occur in the nail plate and move distally as the nail grows out. They are classically thought to be caused by arsenic intoxication, but many severe systemic insults may initiate them. Muehrcke’s lines were described in 1956 by Robert C. Muehrcke in an article entitled “The Finger-nails in Chronic Hypoalbuminaemia.” These represent transverse, double, white lines that are an abnormality of the vascular bed, probably a localized edematous state secondary to the hypoalbuminemia. The underlying causes of these lines include the nephrotic syndrome, liver disease, and malnutrition.

Muehrcke RC: The finger-nails in chronic hypoalbuminaemia, Br Med J 9:1327–1328, 1956.