"Green Apples" are a hybrid of green Cranwelli X Green Caatinga. They do look quite different from a normal green Cranwelli. They usually sell for more too because they are a hybrid. Unfortunately, Apples tend to have a lot of health issues. They are bred for their color not health. Many of them don't survive to adulthood. :-(

Of course, it is also very possible that the petstore has the frog mislabeled- either by accident or on purpose. Can you get a picture of it??