The extent to which you think they’re the same is going to depend heavily on
your long term moral discounting rate (if it’s high, then you’re going to be equally concerned between highly destructive events that very likely won’t kill everyone and comparably destructive events that might),
your priors on specific events leading to human extinction (which, given the lack of data, will have a strong impact on your conclusion), and
your change in credence of civilisation flourishing post-catastrophe.
Given the high uncertainty behind each of those considerations (arguably excluding the first), I think it’s too strong to say they’re ‘not the same at all’. I don’t know what you mean by fields only looking into regional disasters—how are you differentiating those investigations from the fields that you mention that the general public has heard of in large part because a ton of academic and governmental effort has gone into it?
Thanks—agree or disagree with it, this is a really nice example of what I was hoping for.