Comparison should include the

• desktop
• network
• mobile device OS
• Internet of Things (IoT)
• embedded systems. 

Process/Skill Questions: 

• What are the minimum installation requirements for the current version of Windows?
• What are some primary differences between the graphical user interfaces (GUIs) of various versions of Windows? How do those differences affect usability?
• When would using Linux be preferable to using Windows? When would it not?