Sublimerge is not yet another diff plugin for Sublime Text. In fact, it is the most advanced and full-featured plugin that turns your favorite editor into a professional side-by-side comparison and merging tool with amazing features!
install plugin
If Sublimeit is installed Package Control, enter it directly Command+Shift+P(under Mac) sublimerge, search and click to install it yourself, without restarting sublime.
use plugin
Open the two files to be compared under sublime. In one of the files, right-click and select "sublimerge" –>> "Compare to ***"
Summarize
In addition, the unsaved comparison is also a very interesting function. Sometimes I forget where I have modified it. Right-click and select "show unsaved changes
References: