you’re right

Like Reddit, lemmy is based around communities and hierarchical comments (plus downvoting).

Mastodon, like Twitter, is a single timeline from people you follow (and sometimes people they follow and repost), as well as hashtag searching etc. It has no downvote option, but thanks to ActivityPub you can post to lemmy from mastodon and liking something is equivalent to an upvote.

I was promised my giant tortoise would live until at least age 200 when I ordered him on amazon