Bottom Top Margins are off when printing from Illustrator PDF

Once I create a Illustrator document size 8.5x11inch, I save as PDF with Illustraor Default. When I print it, my bottom margin is three times as large as my top margin.  I know is not a printer problem because when I make my background in Word all black and print from pdf- my margins are 1/8 of inch on all sides (see attachment). [Note the white box is only there for saving ink.] But when I do an 8.5x11in box on Illustrator and save as the letter size document, I get the bottom margin much larger.