Does anybody know the difference between Max. Cargo Capacity and Max. Luggage Capacity for automobiles??

I am comparing SUVs for potential purchase I would like to know the difference in this specification.Does anybody know the difference between Max. Cargo Capacity and Max. Luggage Capacity for automobiles??
This is a guess, but I would think that max cargo capacity would imply the weight of all cargo, including passengers, so the combination of the full interior of the vehicle. Max Luggage capacity would be the size of the area where luggage and other items would be placed to transport it. It would be like... in a sedan type car...the size of the trunk... but with an SUV, there is usually a rear area plus a rack on the top of the vehicle... that rack on top would add to the possible capacity for carrying luggage or other items for transporting them, but of course you couldn't put passengers up there... well I suppose you could, but it wouldn't be pretty! *imagining the dog's face while he's hanging his head out the window compared to him being bungee'd to the roof* YIKES!