IDictionary<TKey, TValue> vs. IDictionary

Enumerating directly over an IDictionary<TKey,TValue>returns a sequence of  KeyValuePair structs:

public struct KeyValuePair <TKey, TValue>
{
　　public TKey Key { get; }
　　public TValue Value { get; }
}

Enumerating  over  a  nongeneric  IDictionary returns  a  sequence  of  DictionaryEntry structs:

public struct DictionaryEntry
{
　　public object Key { get; set; }
　　public object Value { get; set; }
}