Both the shell command and perl script are using /usr/bin/chromium.

How is the "profile" option different from: data_directory => '/home/rwk/chrome-session-for-walmart'.

In the chromiun man page it says:

--user-data-dir=DIR
              Specifies the directory that user data (your "profile") 
+is kept  in.   Defaults  to
              ~/.config/chromium  .   Separate  instances of Chromium 
+must use separate user data
              directories; repeated  invocations  of  chromium-browser
+  will  reuse  an  existing
              process for a given user data directory.
[download]

In the WMC doc it says:

profile
profile => '/path/to/profile/directory'  #  set the profile directory
By default, your current user profile directory is used. Use this sett
+ing to change the profile directory for the browsing session.

data_directory
data_directory => '/path/to/data/directory'  #  set the data directory
By default, the current data directory is used. Use this setting to ch
+ange the base data directory for the browsing session.
[download]

What's the difference between "profile directory" and "data directory"?

The profile option is used for the Chrome --profile-directory option, but that doesn't change anything for me. What works for getting the "current" cookies is the data_directory option.