While Allure of the Seas and Oasis of the Seas belong to the same "Oasis Class" of Royal Caribbean ships and share the same fundamental "neighborhood" layout (such as Central Park and the Boardwalk), they are not identical. Oasis of the Seas was the first of the class, launched in 2009, while Allure followed in 2010. Over the years, both have undergone significant "Amplification" renovations that introduced different features. For example, Oasis of the Seas received the "Ultimate Abyss" slide and the "Portside BBQ" restaurant during its 2019 refit, features which may differ on Allure depending on its most recent dry-dock schedule. Structurally, Allure was actually found to be about 50 millimeters longer than Oasis due to slight temperature variations during the steel cutting process, though they are technically considered sister ships of the same size. Their entertainment offerings also differ, with each ship typically hosting a different Broadway-style musical in their main theaters.