A hitch will have two different weight ratings on it - the weight carrying and the weight distribution. Weight carrying is what the hitch is rated for if you’re towing straight off a ball mount. Weight distribution raiting is what the hitch is rated for if you’re using a weight distribution hitch.
For example, you may have a vehicle that’s rated to tow 3,500 lbs weight carrying, and if you’re using a distribution height, the weight distribution rating may be 6,000 lbs. This is because the weight distribution hitch distributes the weight on the hitch, putting less stress on it.