Gross weight is the actual weight of the car at a certain moment. If you load the car's roof box with 50 kg of cargo, the car's gross weight increases by 50 kg. Gross weight thus varies depending on load and equipment.
Car's kerb weight: The weight of the car with the driver when it is unloaded and fully equipped (with tools, spare wheel, fuel, engine oil and water).
Trailer's kerb weight: The weight of the trailer when it is unloaded.
Gross weight: The actual weight of the car or the trailer at a certain moment. This means the gross weight varies depending on load and equipment.
Maximum load: The car or trailer's maximum permitted load according to the registration certificates.
Total weight: Kerb weight + maximum load.