1) Winners and Prizes: Displayed in the challenge details (Top Photo, Top Photographer, etc.).
2) Participation Bonus: Every participation in a challenge (except Flash) rewards 10 Coins.
3) Level Bonus: Reaching certain levels (*) in a challenge rewards Coins.
4) Achievements (Top 10, Top 100, Top 30%, etc).
(*) Top 50 Achievements:
You can't receive both the Top 50 Photographer and the Top 50 Photo achievements and prizes. Only one will be awarded: the higher achievement, which is the Top 50 Photographer.
Winners can only receive one prize bundle per challenge. This means that if you rank in the Top 50 category in addition to winning the challenge (as Top Photo, Top Photographer, or Guru's Top Pick), you will not be eligible for the Top 50 prize or achievement.