One great way to get the word out about new ICOs is by giving away some free tokens. This is sometimes a new concept for some people.
When the forking (Bitcoin gold) happened, those who hold BTC were entitled to a corresponding value of tokens on the new network. This is normally called automatic airdrop.
Incentivized, on the other hand, engages people to perform some tasks (sometimes promoting the upcoming ICO) to get some tokens as reward.
However, there's been some kind of variation in the process. Some airdrops touch on different approach (more direct) offering giveaways on which people just have to claim like a faucet.
For instance, see this article:
https://www.quora.com/What-new-ICOs-are-giving-away-free-tokens-right-now/answer/J-D-EviesIt shows how easy some cryptocurrency airdrops are becoming. Maybe, we'll be seeing other similar airdrops. And obviously, more people will be alert to collect them.