Hashtable

• The System includes a hashtable. namespace for collections.
• Since hashtables are weakly typed collections (not generic), they may hold key-value pairs of any data type.
• Hashtable is secure for threads.
• When a key that does not exist is searched for, Hashtable returns null.
• Due to packaging and unpacking, data retrieval takes longer than dictionary searches.

Dictionary

• The Dictionary is a part of System.Collections. universal namespace
• A general group of items is the dictionary. Consequently, it can hold key-value pairs of particular data kinds.
• In Dictionary, only public static members are thread-safe.
• If we try to find a key that doesn’t exist, Dictionary throws an exception.
• Hashtable is slower in terms of data retrieval.