GitHub's own documentation is unambiguous about this: Copilot always submits a Comment review — never Approve, never Request changes. It does not count toward required approvals. It does not block a merge.
That is a sensible safety boundary. It is also the single most misread fact in AI code review procurement, because the pitch deck says "automated code review" and your brain fills in "quality gate."
Those are different products. Knowing which one you are buying is most of the decision.
Four checkpoints, not four competitors
A governed change passes through four checkpoints. Different tools staff different ones, and the interfaces look deceptively similar because they all produce comments.
