Complex sentence: She no longer holds this distinction after the construction of Royal Caribbean International's in April 2006 However, this vessel has also been surpassed in size but the "Queen Mary 2" remains the largest ocean liner (as opposed to cruise ship) ever built.
Split into simpler sentences: She no longer holds this distinction after the construction of Royal Caribbean International's in April 2006. Although later cruise ships are larger, the "Queen Mary 2" remains the largest ocean liner (as opposed to cruise ship) ever built.