Ultra-Voyager was the name given to the new class by Royal Caribbean. (Voyager class was Eagle class when it was on the drawing board).
Ultra-Voyager, i.e., Freedom class ships, are IDENTICAL to Voyager class ships in size, except that they are longer. Not wider, just longer. If you close your eyes, you would not know which ship's aft section you were in. (Voyager, Explorer, Adventure, Navigator, Mariner, Freedom, Liberty, Independence). As described by others, the extra length puts more space in the Royal Promenade, and throughout that central area, up to the pool deck.