A commercial garage is a place where people store or repair vehicles that burn volatile liquids, such as gasoline, liquid propane, and alcohol, according to writer Mike Holt.
The requirement is a bit more detailed, but this is the general idea. Article 511 also draws a distinction between a parking garage and a commercial garage used for repair or storage.
Major repair garage is a building or portions of a building where engine overhauls, painting, body and fender work, and repairs that require draining of the motor vehicle fuel tank are performed, including floor space used for offices, parking, or showrooms.
A minor repair garage is a building or portions of a building used for lubrication, inspection, engine tune-ups, replacement of parts, fluid changes (for example, oil, antifreeze, transmission fluid, brake fluid, air-conditioning refrigerants, and so forth), brake system repairs, tire rotation, and similar routine maintenance work, including floor space used for offices, parking, or showrooms.