words, the differences are what you _could_ tell Git to
further add to the index but you still haven't. You can
stage these changes by using linkgit:git-add[1].
-+
-If exactly two paths are given and at least one points outside
-the current repository, 'git diff' will compare the two files /
-directories. This behavior can be forced by --no-index or by
-executing 'git diff' outside of a working tree.
+
+'git diff' --no-index [--options] [--] [<path>...]::
+
+ This form is to compare the given two paths on the
+ filesystem. You can omit the `--no-index` option when
+ running the command in a working tree controlled by Git and
+ at least one of the paths points outside the working tree,
+ or when running the command outside a working tree
+ controlled by Git.
'git diff' [--options] --cached [<commit>] [--] [<path>...]::