Windows Vista and Windows 7 are examples of different versions of an operating system.
Explanation:
Microsoft built Windows Vista operating system for use on 'personal computers' like desktops used in home and business establishments, laptops, tablet PCs' and media center PCs
Microsoft built Windows 7 'personal computer operating' system as a unit of the 'Windows NT' family of 'operating systems'. It was released within three years after Windows Vista was released.