Developer guidebook for migration from 1.5.x to 2.0

Hi!

I have done a quick search but did not find any specification, what are the main differences between Opencart 1.5.x and Opencart 2.x, except "Responsive desing, new frontend and new backend etc."?

E.g. - I need to migrate a bunch of modules, and custom controllers for my site.

I know, that there are changes in main Classes and Methods, but even in official documentation did not find "Changes".
Can You help me with any link?

here is a few:

http://www.opencartnews.com/news/opencart-2-whats-new/

- espessially usefull for me is the ability to make custom fileds in address area for Invoice information