What is the difference between FILL-OUT and FILL-UP?

Philippines
May 8, 2009 10:22pm CST
filling up/out a form - application form
...or are they one and the same? Which is more appropriate to use? "Fill-out a form." or "Fill-up a form"? Do you even put a dash in between or are they separate words? Calling all English wiz out there!I'd very much appreciate your help. And please please don't tell me to just google it! (^_^)