Crab rangoons are just a very specific type of fried wontons with a creamy filling involving crab meat and cream cheese, but in the US, it's people's first introduction to wonton wrappers, hence the confusion. Crab rangoon isn't a traditional Asian dish, however, but rather an Americanized version of traditional fried wontons. The takeaway here is that once you learn how to make fried wontons, you can change the filling to anything you can dream of!