premise: There is a little blond-hair girl with a green sweatshirt and a red shirt playing on a playground. hypothesis: The girl is wearing a dress.
contradiction: Sentence 1 states a little blond-hair girl. Sentence 2 just states a girl and does not tell us the color of her hair.  In sentence 1 the girl has on a green sweatshirt and a red shirt which is in direct contrast to the dress she is wearing in sentence 2.  Sentence 1 states she is on the playground but sentence 2 does not indicate where the girl is but most likely being in a dress she is not on a playground.