Interestingly, if I make a .pdf of the file, the background has different
border margings than if I print directly to a printer.
The background and the foreground are usually the same size. What you may be
seeing is the printer margins. To handle the paper, there is usually an area
around the edge of the paper where the printer will not print. Otherwise the
rollers will be smudging or getting gummed up by the ink. There are full
bleed printers that will print up to the very edge of the paper, but they
are not the standard and are slightly more expensive to be able to handle
the page without affecting or being affected by the ink.
John... Visio MVP