Nginx 1.4.x vs 1.2.x

So, I'm trying to make heads and tails of the different nginx verisons.

On the download page (http://nginx.org/en/download.html), I see that 1.4.1 is the current stable version, and 1.2.9 is the most recent legacy version.

Looking at the changelog for 1.4.1, I see it actually includes changes for 1.3 versions as well as 1.2.0. Why wouldn't there be a separate version "branch" for 1.3?

Aside from comparing each entry in the changelog between the 1.4.x version and the 1.2.x version, is there somewhere I can view the major differences between the two?

I'm starting a new project and would like to know these differences before selecting a version.

Thanks