Authentification Method and Privacy level setting for data source explanation

Hi everyone,

I am editing my data source credentials on my personal gateway.

Can someone explain to me the following terminologies.

- Authentication Method: WindowsWithoutImpersonation

- Privacy level setting for this data source: none, private, organizational, public

What would any of the permutations do ? i.e: 

a) WindowsWithoutImpersonation ; none

b) WindowsWithoutImpersonation ; private 

... and so on

Thank you very much for your help and time.