About.com Middle Eastern foods explains that both corn and vegetable oils are used interchangeably in the kitchen. However, corn oil is made from the germs of corn kernels; and, vegetable oil is derived primarily from soy beans. Vegetable oil can sometimes be a blend of different types of oils.
Vegetable oil has a very mild taste, even at room temperature. So it has an appealing taste in foods that are served cold or at room temperature, such as mayonnaise. Corn oil, on the other hand, takes on a different flavor when it is heated versus when it is served at room temperature. At room temperature, it has a slight hint of corn flavor. For this reason, corn oil is not recommended for foods served cold or at room temperature. When corn oil is heated, however, its flavor profile transforms, making it a particularly good choice of oils for frying.
Both corn oil and vegetable oil are considered part of the category of "all purpose" oils. This means that they can be used for a wide variety of purposes and food preparations as opposed to specialty oils, such as rapeseed or coconut oil, which are more prominent in the preparations of certain types of cuisines.