Business Unit ,Security Role,Privilege and Access Level

Business Unit :
A scoping mechanism that defines a grouping of users for security modeling purposes.
Business units are hierarchical in nature.
Business Units are framework upon which a security model is built.

Security Role :

A collection of privileges that reflect common roles of your organization or business units.

Privilege (Access Rights)
The definition of specific type of data access or action that can be granted as a right;
Privileges are granted through a security role and are cumulative
The following privileges that can be assigned :

1. Create 2.Read 3. Write 4.Delete 5.Append 6.Append To 7. Access 8.Share

Access Level :
The Access Level defines exactly to which records the privileges apply.

 1. None 2. User 3.Business Unit 4.Parent : Childs Business Unit 5 Organizations