I do not think that there are any significant differences; however, there is a new class called MemoryCache.
ASP.NET 4 adds extensibility to output caching, which allows you to configure one or more custom output cache providers. Output cache providers can use any storage engine to store HTML content. These storage options may include local or remote drives, cloud storage, and distributed caching mechanisms.
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ASP.NET (). , --. Windows Forms WPF System.Web.dll, ASP.NET. ,.NET Framework 4 , , . System.Runtime.Caching.dll API System.Runtime.Caching. :
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( MemoryCache).
MemoryCache ASP.NET, ASP.NET. API- System.Runtime.Caching , Cache ASP.NET, API.
http://msdn.microsoft.com/en-us/library/s57a598e.aspx