Susan, you can't compare them 100%. There are some things the same and some things different. One huge difference is the casino on Carnival. I have cruised on many different lines, they all have their good and bad points. I would have to say the food on the 2 Carnival Cruises I sailed was top rate. The food on the Wonder was Institutional at best. The shows on Carnival are not Disney, but I thought Disney Dreams was a luke warm redo of the smae old same old. Carnival ships are HUGE, and have lots of bars and lots of late night adult activites. The Disney ships are not so huge, but certainly beautiful.
Go and enjoy it for what it is, a great week on a ship! Have a fabulous time, but don't fall overboard!