The IDERA SQL Secure Windows Accounts tab lists the collected Active Directory users and groups that have permissions on SQL Server objects such as database tables. This tab also displays the associated domain, account name, type, and access information for each account.
Difference between Windows and OS Windows accounts
Windows Accounts
Users and groups that have access to SQL Server objects, such as database tables, either through association with a SQL login or permissions inherited from group membership
OS Windows Accounts
Users and groups that have access to OS objects, such as registry keys or files, either through direct permission assignment or group membership