- From the terminal
If you have the mvim script installed (it is in the dmg, just put it somewhere in your PATH), you can just type in a shell:
mvim -d file1 file2
You can alias this to mvimdiff if you like.
- From within macvim
In macvim, like in vim , you can also use:
:e file1 :diffsplit file2 or :vert diffsplit file2
The second option gives you a vertical diff, which is usually more readable