Aluminum and alloy wheels both refer to the same thing. Alloy is a shorter and another word for aluminum wheels. These wheels can be manufactured by casting or by forging. To cast them, the wheels are molded in hot liquid. Once they are molded, they are then cooled down, which allows the wheel to be both heavy and light.
This method is cheaper than forging the wheels. Aluminum and alloy wheels are great for mild climates. They also provide fast acceleration in a lightweight body. Despite the lightweight, they are both strong. The wheels can be painted or left at its natural state.