What are the different scenarios under which a Business Area or a Profit Center may be defined?

This question is usually very disputable. But both Business Areas and
Profit centers are created for internal reporting. Each has its own pros
and cons but many companies nowadays go for Profit center as there is a
feeling that business area enhancements would not be supported by SAP
in future versions.

There are typical month end procedures which need to be executed for
both of them and many times reconciliation might become a big issue. A
typical challenge in both of them is in cases where you do not know the
Business Area or Profit Center of the transaction at the time of posting.