A bounty program, an airdrop, a campaign,... are sometime the same method or not for free token distribution. A bounty usually request to follow fb group, twitter, reddit, YT channel, Telegram,... Generally, it's very good way to earn free tokens. You can find the bounty program through the bitcointalk forum and many different social forums...
A bounty program is beneficial for earning cryptocurrency. Social media and bitcoin talk are ideal place for bounties. At present i am involved in ENLTE signatute campaign based on blockchain.