A vista can be defined as a distant view or prospect, especially one seen through an opening, as between rows of buildings or trees. Alternatively, it can be defined as an avenue or other passage affording such a view.  Therefore, a vistaprint is a print of a distant view or avenue/passage affording such a view.

A vista print can take many forms, including the form of a painting, a drawing, or a sketch.  Vista printing is a form artwork for some, who enjoy seeing sceneries printed.  Whatever a vista print means to you is the true definition.