When looking for an ISO, you will generally encounter three primary editions:

If you are a developer or work for an enterprise with a Visual Studio Subscription (formerly MSDN), you can access the full, non-evaluation ISOs. This is the "cleanest" version available for production use. 3. Volume Licensing Service Center (VLSC)

Would you like to know more about the features, installation process, or licensing of Windows Server 2012 R2?

Use a tool like Rufus or the Windows USB/DVD Download Tool.