.NET Framework is a set of library/ddls provided by Microsoft which can be used to develop programs. You can use any language(VB.Net, C#, VC++, etc) to write programs which will use .NET Framework. In order to run any programs developed in .NET Platform u need to have .NET Framework in ur machine.

.NET Platform is a generic term to represet .NET languages like vb.net, c#, etc, where as .NET Framework is a defined set of dlls which can be used by any .NET Compatible program.

The .NET Framework is a DLL used to implement the .NET platform, which is the general term for the "technology." So really there's no difference.