The Secret Garden vs Heidi vs Pollyanna

Ok I have read the dicussion about the user that compares The Secret Garden to Heidi. I have to say that Pollyanna paralles Heidi much closer. Heidi teaches Peter. Pollyanna teaches Jimmy Bean. Heidi and Pollyanna both are cheerful and make everyones life brighter.
At the beginning Mary is very sour nasty and not at all like Heidi and Pollyanna. Dickon shows Mary the garden. Mary does not teach Dickon any lessons. Peter is taught by Heidi.
The only parallel is Clara and Colin. Clara was nice and her father loved her regarless of her situation. Clara was not going to die as Colin said he was going to. Colin declared himself to be in a much worse situation. Colin claimed that he was on his deathbed, and that he was a huntchback and that he was crippled and above all else he had created his own sickness.
We are never told in Heidi exactly why Clara was supposedly crippled. I have seen movies that say that she was in an accident or that she got scarlet fever when she was little. In the book we are never told to my knowledge.
The last difference in the end was the final outcome. Colin was walking "as strongly and steadily as any boy in Yorkshire" whereas Clara was just beginning to walk.
I belive that the greatest differerence in the books was the characters beginning personalities. Colin and Mary were sour and hysterical. Clara Heidi and Pollyanna were all sweet and caring children.