There is a difference between sweating and oiliness of the skin; sweating is caused by the secretion of sweat by the sweat glands and oiliness is due to the secretion of oil by the sebaceous glands.
Sweat is secreted by the sweat glands and becomes mainly sodium chloride and potassium, magnesium, calcium, lactic acid, and urea nitrogen. Usually can be divided into by the external environment temperature rise, or body heat production caused by increased perceptual sweating and sweating caused by mental tension, normal people do not realize that evaporation of about 600 to 700 milliliters of water in 24 hours.
Skin oil is secreted by sebaceous glands, and the secretory part of sebaceous glands is vesicular, consisting of multiple layers of glandular cells. Sebaceous gland follicles in the center of the cell cytoplasm filled with lipid droplets, after the disintegration of lipid droplets with the discharge, that is, sebum. The sebaceous glands mainly moisturize the skin and hair, thus playing a role in preventing skin dryness.
There may be other differences in the mechanisms of skin sweating and oil production, as well as synergistic effects, which should be considered on a case-by-case basis.