Paul - thanks for the details. I guess I need to look more carefully at the ships themselves. I was assuming the major differences between the lines were in service and the amount of automation on Wind Star.
We have seen both Royal Clipper and Wind Surf (I think) in port but not at the same time of from the same distance.
All I ask is a tall ship and a star to steer her by; John Masefield
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014, Regal 2014, 2016, Royal 2017
Star Clippers: Royal Clipper 2015