The ships on Carnival are certainly more glitzy than on Princess. The lounges may be a bit livelier at night, but that probably depends on the ship and the passengers on that particular cruise. I find that the food is pretty equivalent. Princess controls the teens better than Carnival. I find the excursions just about the same. The service on both of these lines are pretty equivalent, maybe Princess has it by a bit, but not much. I think that if you ask a Carnival devotee which is better, he say "Carnival", and vice versa for a Princess devotee. Personally, I would rather be on Princess, but I'm not against going on Carnival again.