You can see the differences at http://media.royalcaribbean.com/content/shared_assets/pdf/menus/beverage_packages.pdf. The ultimate is a combination of premium and the Royal Replenish package. That means the ultimate includes extra non-alcoholic options that aren't included in the premium package such as specialty coffee, fresh orange juice, sparkling water, etc.
No extra booze options in Ultimate than in Premium.
NOT in Premium:
sparkling water
fresh squeezed OJ
espresso drinks (or other fancy things from the espresso stand) or Tazo tea. (aka "Premium Coffee/Tea")
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