Mineral oil and castor oil are different things. Mineral oil is made from nonvegetable materials and is usually produced as a by-product of the process of distilling petroleum. Castor oil is made by pressing castor oil plant seeds.
Mineral oil is often used to moisturize dry skin and soothe minor skin irritations. It is a common ingredient in skin care products and cosmetics and is also used in industrial settings as a hydraulic fluid, coolant and lubricant.
Castor oil is taken orally as a laxative. It also has a wide variety of industrial uses. Castor oil is used as a lubricant in race car and jet engines, and it is an ingredient in many products, including cosmetics, dyes and caulks.