Royal Caribbean and Carnival are both racing to build private resorts. Here's how they compare.

Royal Caribbean and Carnival are both racing to build private resorts. Here's how they compare.

Renderings show plans for Royal Caribbean's Perfect Day Mexico and rival Carnival's Celebration Key.Royal Caribbean International, Carnival Cruise LineLarge cruise lines are expanding their collections of private islands and resorts.Royal Caribbean has been a leader with its themepark-like island. Now, competitors like Carnival are coming.Here's how Carnival's Celebration Key and Royal Caribbean's Perfect Day Mexico compare.Royal Caribbean might…