Usually you earn tokens worth very little with airdrops (but you don't need to do actual work). Bounties it depends, I have earned very little sometimes (worthless) or I have been pleasingly surprised with more than USD 500 worth of tokens. I only do bounties for projects I like and invest myself, it is a way to earn more tokens you like on top of your investment, like the cream on top of the pie.
All information is not wrong, he's right airdrop won't let you earn much but in bounties it's but you have to work every week for their requirements as for me i join both. I join airdrop and right now i also join bounty campaign in their signature campaign. Doing both would benefit you in the future.