P&O and Princess were pretty much one line when they were absorbed by Carnival..which incidentally was announced while I was sailing on the inaugural cruise of Star Princess in 2002. Singapore to LA. Loyalty points were shared by the two lines. In fact, it has only been in the last few years that that sharing ceased, at least with P&O-UK.
And though they may be a ‘new’ class of ship within the Carnival brand, ships of that class still sail from North America. Caribbean Princess is the Golden and Star with another deck added, and has the Skywalkers lounge - the shopping cart handle - off the back. Ruby, Emerald, and Crown are the same ship without the handle.
It’s too bad the Pacific Explorer (former Dawn Princess) is a 1997 build. She is the right size to fit into the Fantasy class ports, and was built with balconies, rather than having them tacked on. EM