University - any difference between Dorm and Residential?

My sims that are living in their own homes can still get food from the cafeteria at the commons but they usually have to wait a few minutes for the cafeteria server to arrive. The food is free from their own commons but they have to pay when they visit the other university's commons. Even sims who aren't attending university can use the cafeterias but they have to pay at both of them.