And apparently they decided that her finished version (as appearing in the first Luna-centric episode since the pilot) was actually neither of these models. It's somewhere in between, retaining the same cutie mark and general shape as Nightmare Moon, but with the skin color of tiny Luna. Her hair is also a blend of tiny Luna's and Nightmare Moon's. Interesting look, and I like it.



Also, she's normally slightly smaller than Princess Celestia but quite obviously larger than any of the other ponies. Your version is not wrong, as it is indeed using both of her versions from the pilot, but they just changed her later on.