The answer to this question depends heavily on the situation and the relationship you have with the offender. When you block someone on nearly any platform, they can't see anything you post, your profile, or send you messages (and vice versa). When you mute someone, you're hiding their online activity, but they can still see everything you post. If you want to hide what you're doing, then use the blocking feature. If you want to hide their activities but don't mind them seeing yours, mute them.