These seem to only filter by tags/keywords. Feeds are a lot more powerful than that.
That's what I meant with:
>> "It's hard to explain because it sounds like tags or saved searches if you're trying to relate it to the more common model of social media."
For example: a feed that's something like a "For You" timeline without the commercial incentives to make it bad (it's empty without an account because it has nothing to work with): https://bsky.app/profile/did:plc:tenurhgjptubkk5zf5qhi3og/fe...
It's not just blunt filtering. Feeds can (and do) apply machine learning, take input from your interactions, and generally do all the things a first-party timeline can do.