Vegetable shortening and vegetable oil are not the same. Vegetable oil is derived from plant sources such as seeds. Manufacturers create shortening from vegetable oil through a process called hydrogenation, which creates a solid fat. Thus, vegetable shortening may contain more saturated fat and trans fatty acids than vegetable oil.
Cooks typically use vegetable shortening as a replacement for lard, butter and other solid fats. Its flavor is neutral and does not mask the flavor of food. Shortening also makes cakes tender and pie crusts flaky. Vegetable oils, on the other hand, may be more suitable for frying, sautéing and other cooking methods that need liquid fat.