How closely does Princess Tutu follow Swan Lake and The Nutcracker? I know that the Princess Tutu anime uses a lot of music and performances from the ballets Swan Lake and The Nutcracker. However, does the anime's main plotline -- of a princess who helps return the prince's heart to him, only to die upon confessing her love -- closely follow either story? If so, what are the major deviations?
The story is loosely based on this, but it actually revolves more around bending the inevitable fate thrown to Ahiru (Tutu) by third side of the story. The storyteller, if you prefer.

The ending of the anime is not same either, even though it uses the same kind of theme. IMHO the ending is most closely following the original story, if you look the big picture.