An auto show, or motor show, is a public exhibition of current automobile models, debuts, concept cars, or out-of-production classics. It is commonly attended by automobile manufacturers. Most auto shows occur once or twice a year. They are vital to car manufacturers and local dealers as a public relations exercise, for advertising products, and for increasing publicity.
There are other auto/car shows that occur on a more frequent basis, like weekly. It's not known if there is a regularly accepted term for these more frequent, informal "car rallies" or "car enthusiasts events". Some meeting events have themes, such as classic cars, hot rods, etc. In any case, these car gathering events are more localized, typically consisting of car enthusiasts who meet to socialize and enjoy their enthusiasm with other car owners.
The Organisation Internationale des Constructeurs d'Automobiles organises many auto shows.
They are distinguishable from car shows in that auto shows typically showcase new or concept vehicles whereas car shows showcase custom, classic, or exotic cars. They also distinguish in that auto shows are almost always a major professional event whereas car shows can be either professional or amateur and many are locally organised. Auto shows always charge for admission whereas many cities have local, free car shows.