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How to activate or choose between Windows 8.1 (Core) and Windows 8.1 Pro
Before reinstalling Windows backup your data, save Windows version info and product key. See this article.
To choose between Windows 8.1 Pro or Windows 8.1 Core you have to do… nothing!!! Just enter the product key with which your OS has been pre-installed.
If you enter a Windows 8.1 Pro product key, after you click next, you will see the details about the selected OS as in this image below.
If you enter a Windows 8.1 Core product key, after you click next, you will see the details about the selected OS as in this image below.
Using the term “Core” for version 8.1 is not clear. In the official website, installer menu and various Windows of the operating system, Microsoft only uses the term “Windows 8.1”. But in the OS register and in some other functions where the Operating System is identified, there is also the term “Windows 8.1 Core”.