Cases usually protect the whole phone. If you drop your phone your case protects it. Your case will shatter and your phone won't. They are very strong. A cover is used to cover the phone from dirt and dust, not to make it look different. Most are made from cloth, they don't protect your phone the way cases do.
Did you Know
In 1983, a truly portable cell phone called the DynaTAC 8000X was introduced to the world. The nickname of this phone is called the Brick. In 1983, Motorola introduced the DynaTAC 8000X, and it revolutionized the cell phone business. It was a lightweight device which only weighed about 30 ounces. It was called "The Brick" because it closely resembled a brick used for construction- it had the same shape as a brick.