泛型集合和非泛型集合之间存在微妙和不那么微妙的差异。它们只是使用了不同的底层数据结构。例如，Hashtable保证了一个写入器-多个读取器而不需要同步。字典没有。

它们在智能感知上拼得很好。只需输入System.Collections。或者System.Collections.Generics(首选)，你会得到一个可用的列表和简短描述。

下面是给你的一些建议:

You can use foreach on types that implement IEnumerable. IList is essentially an IEnumberable with Count and Item (accessing items using a zero-based index) properties. IDictionary on the other hand means you can access items by any-hashable index. Array, ArrayList and List all implement IList. Dictionary, SortedDictionary, and Hashtable implement IDictionary. If you are using .NET 2.0 or higher, it is recommended that you use generic counterparts of mentioned types. For time and space complexity of various operations on these types, you should consult their documentation. .NET data structures are in System.Collections namespace. There are type libraries such as PowerCollections which offer additional data structures. To get a thorough understanding of data structures, consult resources such as CLRS.

泛型集合将比非泛型集合执行得更好，特别是在遍历许多项时。这是因为装箱和开箱不再发生。

我能想到的是:

Array* - represents an old-school memory array - kind of like a alias for a normal type[] array. Can enumerate. Can't grow automatically. I would assume very fast insert and retrival speed. ArrayList - automatically growing array. Adds more overhead. Can enum., probably slower than a normal array but still pretty fast. These are used a lot in .NET List - one of my favs - can be used with generics, so you can have a strongly typed array, e.g. List<string>. Other than that, acts very much like ArrayList Hashtable - plain old hashtable. O(1) to O(n) worst case. Can enumerate the value and keys properties, and do key/val pairs Dictionary - same as above only strongly typed via generics, such as Dictionary<string, string> SortedList - a sorted generic list. Slowed on insertion since it has to figure out where to put things. Can enum., probably the same on retrieval since it doesn't have to resort, but deletion will be slower than a plain old list.

我倾向于一直使用List和Dictionary——一旦开始使用带有泛型的强类型，就很难再回到标准的非泛型了。

还有很多其他的数据结构，比如KeyValuePair，你可以用它做一些有趣的事情，还有SortedDictionary，它也很有用。

关于高频系统交易工程的哈希表与字典的一个重要注意事项:线程安全问题

Hashtable是线程安全的，可以被多个线程使用。 字典公共静态成员是线程安全的，但任何实例成员都不能保证是线程安全的。

因此，Hashtable仍然是这方面的“标准”选择。