MSDN Library :
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If you are already familiar with VBScript or JScript, notice that you do not use the scripting language’s function for creating a new object instance (CreateObject in VBScript or New in JScript). You must use the ASP Server.CreateObject method; otherwise, ASP cannot track your use of the object in your scripts.
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CreateObject() is specific to vb (or vbscript) engine, and ActiveXObject() is specific to Javascript, but you can use Server.CreateObject() in both vbscript and javascript on the server side