A DUDV map is somethings different then a Normal map.
Here you can see The two maps together.
Notice the funny colors of yellow, red and green? This is called a dudv map. You can probably imagine why it is called that because it's actually the derivative of a normal map. In mathematics the notation for a derivative is du/dv. What this texture does is give us a way to calculate refraction and how the light will react and bend on the object. In our case, our object is the water.
But you won't find any DUDV maps in your pack.
And here you can see the default normal map and one that come with texture pack.
Some people told me that the don't see the difference between the look in game so I have made some screenshots. The water smoothness is on 100%.
I hope its all clear now and thanks for reading.
Rise and shine Fpsc x10...rise and shine.