If your 12 volt batteries are true deep cycle batteries then there is not that much difference.
But many 12 volt batteries are not true deep cycle, but rather a hybrid often called "marine/deep cycle". Their plates are thinner and they don't hold up as well to repeated discharge to 50% capacity or below, which is what your RV batteries may be required to endure.
Here's a link to an article called "The 12 volt side of life" which discusses all sorts of battery applications, including 12 volt and golf cart 6 volt batteries.
Link here