If you win a contest, you get the full publishing perks. Its the same if you campaign to the 750 preorder level. If you are not in a contest or don’t win, but hit 250 preorders, you get the "Quill Level" which means your book will be published, but with lighter marketing help.
Contests are nice because if your book fits the contest’s theme (i.e. Fantasy, Hard Science Fiction, Video Games), you can get all the perks of the full publishing contract without having to hit that 750 goal, which can take months and a lot of time. But, I know plenty of people who didn’t win or were not in a contest who campaigned for the full 750 and made it just fine.
Hope this helps