Basically, get better XP per battle, but the premium account is for WoWS only.
We’re happy to launch a brand new feature: Warships Premium Account. It gives you an extra 15% experience compared to the pre-existing Premium Account (PA), but it’s exclusively for World of Warships. Despite the increased XP yield, the cost of the Warships PA is equal to the cost of the general PA. At the end of a battle, the Premium Account with the highest modifier will be used to calculate your XP bonus.
When the Warships PA is added, players with the active general PA will also get the Warships PA for the same duration. They will be able to try the new feature out at no extra charge.
This feature has been developed in mind for those players who mainly play World of Warships and prefer to receive an increased bonus in one game in exchange for the removal of bonuses in others.