How to compare versions of pages side by side? [on hold]

Comparing two different versions of a web page or article — from a CMS, e-commerce platform, text editor, etc — is a tricky thing to do, as there really isn't any consolidated design pattern to support it. People often need to compare the current state of a web page against an older revision, to raise awareness about:

• Which blocks and pieces of content have changed
• Which user was responsible for those changes
• Whether those changes were published or only saved as draft

Outside the scope mentioned above, there seem to be some good ideas for side by side comparison out there. Github has a great solution for comparing images and Kaleidoscope does text diffing in quite an interesting way, both allowing for multiple ways of comparing versions of images and text, respectively.

Nonetheless, I'm still wondering how CMS, e-commerce platforms, and text editors handle side by side comparison of different versions of the same page or article – containing text (titles, headlines, body copy), media (images, video) and meta data.