Both of them are distinct from "boss" as the grandparent describes it, which is usually what happens when you get a manager who lacks empathy, awareness, and flexibility. Both leader and manager are highly cognitively-complex, pro-active roles that require constant information-gathering. Boss is what happens when you get someone in that position who lacks the confidence or skillset to stay on top of all that information and then reacts through command & control techniques when things go wrong.
That sounds like a boss to me (and not just because you used an unnecessarily gender-specific word ;). One of the anecdotes in the article is about this person, as a manager, acting as a listening board and ultimately conduit for an engineer when discussing the importance of a specific project at Twitter, and raising questions that came from that engineer that ultimately resulted in the project being cancelled. I think that advocacy role is important management – where the manager advocates both up and down (and ultimately you can't "tell" people what to do, you can only fire them or convince them, so it's "advocacy" both directions).