Shame is a feeling, "decent person" is a moral characterization. The former might be part of an insentive structure leading to the latter.

I believe all four combinations exist in practice.

It's the same thing, and both are vulnerable to disingenuous applications of cultural relativism.

You'll see similar arguments on this thread: "shame is just what you don't approve of", etc. Yes, it's just about being a decent person, and no, scientists still haven't discovered a moral axis in the universe that says what that means. Unfortunately we're in a position where we have to explain that "just be a decent person", which is an inclination shared by 95% of people anyway, isn't some vestigial instinct that modern humans should be ridding themselves of.