For me it would have to have an assortment of rides, not just water. If it's all water based, then to me it's a water park.
When I think of theme park for me it's got multiple types. It's got water, plus roller coaster, plus 3d etc.. You got outdoor and indoor, like IOA. You have something like Spiderman, but then Hulk, but also water rides like Popeye and Dudley Do Right. If I want to get wet I have that option, if I don't feel like it then I also have that option.
VB has no options, it's all water based and that to me just makes it a water park. Not a theme park.