The YC Board of Overseers

What is the technical difference between board of directors and board of overseers?

Interesting that this board seems to be constitued by the founders of some of the most successful YC startups (Airbnb, Homejoy, Stripe, Dropbox, Weebly, Twitch)

Very awesome. This seems like a healthy step in a direction I'm personally excited about: YC as a university (vs. YC as a mini VC).

Interesting that PG is not there.

Why not call it "Board of Directors"? The word "overseer" still pretty much only refers to the middle-managers of slave plantations.

Wait, Sam Altman is both the YC president and on the Board of Overseers. If the board is responsible for both hiring/firing the president, how does that work?

Just curious if there is any visibly transparent process in place to add/remove members to the Board of Overseers?