Is there a difference between StringDictionary class and Dictionary

Question

System.Collections.Specialized contains StringDictionary http://msdn.microsoft.com/en-us/library/system.collections.specialized.stringdictionary.aspx#Y1626

What's difference with Strong Typed Dictionary in Generics?

Answer 1

StringDictionary comes from .Net 1, which predates generics.

Therefore, unlike Dictionary<String, String>, it doesn't implement any generic interfaces, so it cannot be used with LINQ (unless you Cast())

Also, StringDictionary normalizes all keys to lowercase.
(To make a case-insensitive Dictionary<String, String>, pass StringComparer.OrdinalIgnoreCase; this is also more compatible with Turkey)