What I have understood from my experience:
MSDN
is more of a social platform which Microsoft uses to build a relationship with developers, engineers around the world; It is surely Microsoft centric but not Windows specific.For e.g. I have read articles in MSDN magazines which were related to general programming problems, C++, Developer blogs etc.
Windows Dev-Center
, on other hand is something that emerged after Microsoft introduced Windows 8, it is purely Windows Centric (Phone & Desktop) focusing developers related to these platform.As stated here
The Windows 8 Dev Center: Everything you need to design, build, and sell a Metro style app
Key thing to note is Windows Dev Center also resides on the domain of MSDN
itself > msdn
.microsoft.com/en-us/windows
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