Difference between Task Level and Assignee Level

Summary

While configuring Expiration Settings we have three options. A good document to explain the functionality would help

Content

Hi All,

While configuring Expiration Settings in PO or any Approval workflow three options exist:

1. Do Nothing - Self Explanatory.

2. Task Level

3. Assignee Level

I would like to understand the difference between option 2 and 3. Also, how do these options work in conjunction with "Maximum Escalation Levels". Also, I do not find all approver titles in the field "Highest Approver Title". Any pointers to documentation regarding this would help. Attached is a screen from BPM.

Thanks, Bala.