Blocking someone cuts all relationships between them (they get unfollowed) and they cannot interact with your questions/answers anymore.

If you mute someone, it will keep following/follower relationships intact, but you will not receive questions from them, nor any notifications if they interact with your questions/answers.

Not currently implemented, but definitely planned: Content of someone you blocked/muted shouldn't show up in timelines.

We're still thinking about how to best approach this, because there's multiple "levels" of content. Hiding answers would be obvious, but if you blocked someone, you can't follow them, so you don't even have their answers in your feed. But should we also hide all answers to questions from that blocked user?

Aside the functional considerations we also are thinking about how to best deal with this technically so it doesn't impact performance too much.