Although car tags and number plates have some similarities, there are some differences between the two. Car tags are just what they sound like, tags that are specified and designed for identifying cars. Number plates are not always required for identification purposes. A person can buy a number plate just for decorations. Also, a number plate can be sold to another person or even a business. Some other differences between car tags and plates may include the color of the tags or plates, the length, the width and the height of the plate, and the longevity of the tags or plates.