I have two cloned repositories of two very similar open-source projects, which I have been working on in different instances in Sublime Text 2 to arrive at my desired result. Co
UPDATE OCTOBER 2017 I never knew this feature existed in Sublime Text, but the interface appears to have changed slightly from the previous answer - at least on OS X. Here are the detailed steps I followed:
This opens a new tab showing the comparison. The first file in red, the second in green.