Difference between type of Secondary Cost Element Category?

Hi,

I checked the system, and during the secondary cost element (CE) creation, I can select some of the CE category as follows:

21 Internal settlement

31 Order/project results analysis

41 Overheads

42 Assessment

43 Internal activity allocation

50 Project-related incoming orders: Sales

51 Project-related incoming orders: Other

52 Project-related incoming orders: Costs

61 Earned value

My question, what kind of report that I can read entries with these kind of CE?

Reason: I want to check what has been posted to these secondary CE.

Or

Could anyone explain the use of above-mentioned CE category in brief?

Thanks.