Hi,

While this isn't something I've personally used before, looking at the documentation it looks like Organization and Division data instances allow for access groups and/or rulesets to be included, which provides any operators which have that Organization or Division the access defined by those access groups or rulesets.  It looks like Organization Unit data instances only relate to work queue access and reporting.

You can read more about this in the below documentation:

https://community.pega.com/sites/default/files/help_v731/procomhelpmain.htm#data-/data-admin-/data-admin-organization/access.htm

https://community.pega.com/sites/default/files/help_v731/procomhelpmain.htm#data-/data-admin-/data-admin-orgdivision/access.htm

https://community.pega.com/sites/default/files/help_v731/procomhelpmain.htm#data-/data-admin-/data-admin-orgunit/related.htm

Hope this helps!

-Kurt