As a basic understanding of different harnesses, I can brief up as follows:
Confirm — To display the results, including the work object ID, of an update.
New — To create a work object. (You can choose a value other than New if desired; identify the harness in the Harness for work object creation field on the Process tab of the Flow form.)
Perform — To update and possibly complete an assignment.
Reopen — To allow a resolved work object to be reopened.
Review — To review a work object and assignment without the ability to update.
Mostly, all the sections embedded like pycaseheader etc., within each harness are same, the difference being will be in the read, write and execute privileges and sometimes the alignment will also differ.