Diferrence between C#'s Dictionary and SortedList?

Question

I was studying the extra lessons about those two collections and could not find a real difference between them, except the methods IndexOfKey() and IndexOfValue(), which are SortedList only (I guess). There are specifications for the use of each?

Answer 1

https://stackoverflow.com/questions/1427147/sortedlist-sorteddictionary-and-dictionary