I can't provide examples, because I'm not at home (so please excuse, if the names may not be 100% correct), but...
1) Display width and height describe the size of the visible area of the game's screen
2) Window.Width and .Height describe the total size of the window used to display the game (meaning: including the caption bar/borders)
3) Window.ClientWidth and .ClientHeight describe the size of the area, where the game is displayed, without caption bar/borders
Try making your UI non-scrollable/non-zoomable and use [0, 0] to [DisplayWidth, DisplayHeight] for positioning.