Quickly compare the files in the left panel with the files in the right
one.  Only the file names, sizes and time stamps are considered in the
comparison.

Compare the files in the left panel with the files in the right one.
The contents of each file in the current panel will be compared against
the contents of its counterpart (if any) from the other panel.

Recursively compare (using diff -r -q) the current directory with
the other panel's current directory (‘FAST-DIFF’).  Print on
standard output the names of the files that differ.

Compare (using diff) the current directory with the other panel
current directory.  For successful operation, both panels should contain
the same directory (‘DIR-DIFF’).

Compare (using diff) the current directory with the other panel
current directory.  For successful operation, both panels should contain
the same directory.  The operation is performed in background
(‘DIR-DIFF’).