This AirDrops gives free Tokens away for a simple task every week.
Payout will be done within a week after the previous week is concluded.
AirDrop amount is smaller compared to bounty at 1,000 RNP(USD$1,000) / week.

Bounty last for the entire ICO and payout will only when the ICO concluded in July.
Bounty pool contains much more tokens compared to AirDrop with 200,000 RNP(USD$200,000).

AirDrop is more of a free token weekly in exchange for simple tasks.

Bounty require more commitment and a longer time, in exchange a higher reward as well.

I hope this clears your question!