As you can see, they are more or less interchangeable. A perfect scenario for a conspiracist. I believe there are even more of them out there, so maybe at one point this pic may have an additional vessel added.
Out of curiosity, when I sailed on the Symphony in 1995, they were talking about building these ships with a GRT of over 100000 tons, and we shook our heads and could not quite see it. Crown Princess measures in at 113000 GRT. Times have changed.