Vista and/or Vista items are used interchangeably in the documentation. Vista can be defined as any individual item that can be displayed or visualized within in the g-Viewer. For instance, when the user selects the Show properties of Common gather - Common gather [View SEG-Y] window, Common gather is a Vista item in the below image.
Similarly, in the location map we have many vista items to display as shown below.
In the above image, we can see many Vista items like Selected trace XY, Selected line, .........etc.