Guaranteed contests attract more entries because you are guaranteeing that you will pick a winner and award the prize money.
If you want freelancers scrambling to create the best contest entries for you, post a Guaranteed contest or make your contest Guaranteed. Just select the Guaranteed upgrade when posting your contest. If the contest is already posted, click Edit Contest on the contest page, select Guaranteed from the optional upgrades section, and click Upgrade Contest.
If you do not award the contest within 30 days after it closes, the prize will be automatically distributed among the qualified entries.*
*The Money Back Guarantee is only available for Regular contests (contests that are not upgraded to Guaranteed).