A crypto faucet asks you to complete simple tasks like watching a video or downloading an app. Airdrops are coins or tokens that are gifted at issuance to highly engaged users of a platform. For example, say I launch a platform called elementalcrypto that does some funky stuff. Then, if after a year, I want to issue and circulate a coin called LMNTAL I may give some of it for free to the most active users of my platform to say thank you and create some publicity.