Хорошо, Вася, давай тогда конкретно с UX Guidelines и на английском
https://docs.microsoft.com/en-us/windows/win32/uxguide/win-window-mgtA
top-level window has no owner window and is
displayed on the taskbar. Examples: application windows. In Windows Vista and later, dialog boxes without owner windows and property sheets are also considered top-level.
An owned window
has an owner window and isn't displayed on the taskbar. Examples: modal dialog boxes, modeless dialog boxes.
...
Minimize. All primary windows and long-running modeless secondary windows (such as progress dialogs) should have a Minimize button. Clicking Minimize reduces the window to its taskbar button. Consequently, windows that can be minimized require a title bar icon.
Maximize/Restore down. All resizable windows should have a Maximize/Restore down button. Clicking Maximize displays the window in its largest size, which for most windows is full screen; whereas clicking Restore down displays the window in its previous size. However, some windows don't benefit from using a full screen, so these windows should maximize to their largest useful size.