When you favourite a toot, that tells the tooter that you've seen it, typically implying you thought it was interesting. Plus, you can look back at all the things you've favourited, like transient bookmarks.

When you boost something, it's to support the tooter or share the content with your followers because you want them to see it too.

Mastodon isn't a game you play with an algorithm or even a popularity contest. On a fundamental level, it's about conversations and interactions. #MastoTips