Each ship does in fact have a unique personality.
I took my first cruise 25 years ago, and have been on 7. The experienced travel agents I worked with always tried to match you to both a ship and an iternary you will like.
"The Mermoz" was a very stuffy formal small ship. 95% of the passengers were from France. Tuxes were required for formal nights, suits for every other dinner. Entertainment consisted of the cruise staff performing, including singing by the captain.
"The Norway" was a classic ocean liner, tiny cabins, but fine service. It was the largest cruise ship in operation when we sailed her. We cruised her twice, and are very sad she is no longer sailing. At the times we sailed the Norway was known for featuring known entertainers on board, Norm Crosby, Jack Jones were the entertainers on our first cruise, The Fifth Dimension and Shields and Yarnell on our second. Some NFL player whose last name was Nixon was the sports celebrity on the first cruise, Moses Malone was the sports celebrity on the second.
"The Nordic Prince" was a younger, hipper ship, smallish, newer. It featured boardway quality shows, but no name entertainers.
"The Soveriegn Of the Seas" was 2 months old when we sailed her, she was the first Megaship, and at the time the biggest. Everything was state of the art, and it featured Broadway type shows.
"The Amsterdam" was a good sized ship, which was known for quality of service.........the line was know for it's "tipping is not expected" police because "top quaility service should be provided without expectation of a tip". Of course everyone tipped. Sadly, HAL has since gone to tipping for the first time in the lines 100+ year history. Again, broadway quality shows, but no name entertainers. But frankly, the best show was put on by the Indonesian cruise staff at 11:30 pm one night, featuring the music, dance and songs of Indonesia. It was a show from the heart, and they rocked the house.
"The Magic" is a class ship, just the right size, without some of the usually cruise features (Casino), but with lots more kids space. Of course it has the Disney touch, but it's not over kill.