fried green tomatoes - Were Ninny and Idgie the same person?

This is a fairly common misconception with the movie. In the book, Fried Green Tomatoes at the Whistle Stop Cafe, it is absolutely clear that the two are separate characters. In fact, if I remember correctly, they are even in some of the same scenes. In the movie however, it is not as apparent. According to the film synopsis on Wikipedia, Ninny describes Idgie as her sister in law. Which would fit with the book, however I don't recall it ever being that specific in the movie. Another large part of the book that was played down in the film is the romantic relationship between Idgie and Ruth.